The space station Dark Space 8 has seen better days. Its heroic crew used to save the cosmos from unspeakable threats on a daily basis, but nowadays there are newer stations with updated technology and freshly trained crews, and Dark Space 8 has become something of a backwater. It is currently hosting the 309th Intergalactic Song Contest, which is being broadcast live to the galaxy by audio personality Logan; however, the contest is notable only because two of the contesting worlds are bitter enemies -- the matriarchal warlords of Angvia and the transcendental gestalt entity known as Gholos. Commander Paul Keele has recently died of the Orion flu despite the best efforts of chief medic Eleanor Harcourt, but his replacement John Ballard is on his way, and Harcourt hopes their working relationship will be as close as her relationship with Keele. However, Lieutenant Strindberg finds that he can’t make contact with the approaching shuttle -- and even the science officer, Professor Ivor Fassbinder, can’t explain the fluctuating chronon wave detected by the station’s sensors.

The chronon wave is presumably caused by the TARDIS, which has just materialised aboard the shuttle rather than in the Parisian restaurant for which the Doctor had aimed. The Doctor and Mel emerge to find two bodies, presumably killed by a poisonous gas which has since dissipated -- and they also find a bomb attached to the ship’s controls. They flee back to the TARDIS, but the bomb goes off before they reach safety. Fortunately, Strindberg managed to get a lock on their life signs and beams them aboard the station as the shuttle explodes. Eleanor and Fassbinder assume that the two new arrivals are Commander Ballard and his pilot, and Fassbinder theorises that the ship was destroyed by an overload of magnetic radiation. The Doctor decides to play along with the case of mistaken identity for the moment.

As Eleanor shows the Doctor and Mel to their quarters, they are confronted by the entrant from Gholos and its human translator, Loozly. Even the Doctor can’t speak Gholos’ language; it took Loozly fifteen years to learn the basic rudiments, and he considers it a far richer form of communication than mere humanoid language. On Gholos’ behalf, Loozly demands an explanation for the explosion of the shuttle, as does the nervous contestant from Cyrene. Loozly points out that the blast pattern indicates the shuttle was destroyed by an Angvian scatter bomb, and fears that Gholos may be under threat. Matters only get worse when Queen Angvia arrives, and Loozly and Cyrene accuse her people of launching an unprovoked attack on the Commander. Angvia herself claims to have no interest in politics, but she too has a complaint -- her billing is too far down in the running order.

The Doctor suggests changing the running order so the contestants appear alphabetically, and he and Mel retreat to their quarters while the contestants continue arguing. The Doctor realises that this is a pivotal moment in the history of Angvia and Gholos; even now, the two worlds are holding a peace conference on Achilles 4 to end centuries of warfare, and this song contest marks the first time representatives of the two planets have been together without trying to kill each other. Mel suggests that the Doctor order Fassbinder to scan the shuttle debris and recover the TARDIS, and although Fassbinder seems slightly distracted when the Doctor contacts him he agrees to do as he asks. However, Mel realises that the Doctor is getting a bit too involved in his role, and reminds him that whoever killed the real Commander Ballard may assume they’ve failed and set their sights on the Doctor...

As more contestants arrive on Dark Space 8, Logan offers commentary on the preparations for the big event, and Eleanor records her impressions of the new commander in her personal log. While Mel checks on Fassbinder’s progress, the Doctor receives an urgent summons to the command deck; Queen Angvia has come to complain about being quartered directly next to the contestant from Gholos. The contest’s neutral arbiter, Geri Pakhar, helps the Doctor to sort out an alternate plan for accommodations. Gholos and Loozly arrive to complain about the same problem only to find that it’s already been sorted out, and they withdraw, Loozly translating Gholos’ protests at this shoddy treatment. Eleanor compliments “Commander Ballard” on his deft handling of the situation. Or may she call him John?

Mel finds Fassbinder singing quietly to himself in the science lab, and when she asks what he’s doing he explains that he’s working on a device to measure proton strings in the 12th dimension to see if they behave differently. He has no data from those experiments yet, and also has no results from the scan of the shuttle debris. He promises to call Mel if he finds anything, but Mel gets the impression that he’s hiding something from her. On her way back to her quarters, she shares a lift with a somewhat standoffish young man, and tries to strike up a conversation with him. The young man’s attitude changes completely when he realises that she genuinely has no idea who he is. He is Nicky Newman, pop singing sensation and the fifth most famous person in the galaxy, and he’s sick to death of his adoring public. Meeting Mel is like a breath of fresh air, as he’s finally met someone who knows as little about him as he does about them.

Eleanor arrives in response to the alarm, followed by the Doctor and Geri, and then Fassbinder. Geri asks the doctor what’s happened to Cyrene, and the Doctor nearly response before he and Eleanor realise that Geri was addressing Dr. Harcourt. Eleanor finds no signs of foul play, until the Doctor points out two puncture marks which she had assumed were part of Cyrene’s protective colouring. As Eleanor takes the body to sickbay, the Doctor and the others retreat to the guest lounge, where they are joined by Angvia, Gholos and Loozly. Loozly, speaking for Gholos, accuses Angvia of murder and demands that the contest be called off, but the Doctor refuses to do so, fearing this could send the wrong signals and disrupt the peace conference. Gholos and Loozly storm out, and Angvia warns the others not to trust Gholos; too many of her people have been killed by the creatures’ legendary “blue stings.”

Nicky wonders if Cyrene could have been killed by the “blue sting of Gholos,” but the Doctor refuses to speculate without facts. The witnesses then go their separate ways. Nicky sets off for an interview, but arranges to meet privately with Mel later; even Angvia and Geri have been gushing over him, and he wants to spend time with someone who treats him as just an ordinary person. Fassbinder returns to his lab, but notes in passing how surprising it is to see a Pakhar, one of the galaxy’s foremost diplomats, acting as the arbiter in a mere song contest. Geri, defensively or politely, insists that this appointment is quite prestigious. The Doctor sends Mel to search for more evidence in Cyrene’s quarters, while he returns to the command deck. A cover story is sent to Logan claiming that Cyrene has dropped out due to ill health. Unfortunately, Eleanor is unable to identify the poison used to kill Cyrene, and Fassbinder then informs the Doctor that the sensor scan of the shuttle debris has found nothing unusual. It seems that somehow the TARDIS has gone missing...

While searching Cyrene’s quarters, Mel is confronted by Gholos, which turns an alarming red colour and crackles loudly as it approaches her. Loozly arrives and intervenes, explaining that Gholos was searching for evidence to link Angvia to the murder, and thought that Mel was attacking it. Loozly takes great offence when Mel advises him to keep the “thing” under better control; he considers Gholos to be far more civilised than any mere human. Gholos continues to crackle, clearly quite upset as it departs with Loozly, and when Nicky arrives, the shaken Mel tells him that Gholos just tried to kill her.

Fassbinder can’t pin down what caused the shuttle to explode. Magnetic space lightning? A cloud of invisible particles? Some new kind of alien energy that can’t be detected by the station’s scanners? Eleanor, realising that her commander is deeply troubled by the loss of his property, assures him that the door to her quarters is always open, just as it was for Paul Keele. Strindberg then informs them that Achilles 4 is under attack by Angvian separatists. The last, best hope for peace between Angvia and Gholos faces failure, and there’s only one thing the crew of Dark Space 8 can do about it -- make this the best Intergalactic Song Contest there’s ever been!

Mel and the Doctor compare notes, and Mel, recalling Fassbinder’s odd behaviour, concludes that he was lying about the TARDIS’ disappearance and that he and Gholos are working together. The Doctor has other ideas, however, having noticed something odd that happened right after they found Cyrene’s body. Before he can come to any conclusions he must mediate between Angvia and Gholos again, as Gholos, through Loozly, insists that the song contest be cancelled due to the Angvian attack on Achilles 4. The Doctor assures Loozly that Gholos is perfectly safe, and Gholos and Loozly storm off when Eleanor reveals that she’s been unable to identify the poison used to kill Cyrene -- or even if she was poisoned at all. Before leaving, Angvia invites the Doctor to dine with her, as Angvian warriors traditionally dine with the chief of the village they are visiting. The Doctor accepts the invitation.

Nicky and Mel take advantage of a lull in events to slip off to the station’s swimming pool, where Nicky asks Mel about herself. Trying not to blow her cover, she changes the subject to Nicky himself, but soon regrets it as he begins to rant about his lack of privacy. Everyone in the galaxy thinks they know him, and they have an opinion about him before they’ve even met. The flight to Dark Space 8 was a nightmare of screaming fans and giggling stewardesses; only Loozly was kind enough to talk to Nicky and lend him an aspirin for his headache. Despite the stress, however, Nicky feels he owes too much to his manager, his mother and his fans to just walk away. His stomach churns just thinking about it, and even as he complains he is called away for another interview. When Mel advises him to ignore the call, he snaps angrily at her for presuming to understand what his life is like.

Mel returns to the guest lounge, where she finds the irritated Loozly listening to Logan’s cynical commentary. Some people criticise Logan for commenting on the songs when he can’t even pronounce their names, but this year, he’s answered his critics by building his own translation device so he can give the contestants a fair shake before shredding them. Mel is surprised to see Loozly without Gholos, but he explains that Gholos is resting and shows her the device he’s using to monitor Gholos’ vital signs and ensure it doesn’t suffer too much from its separation from the gestalt. Loozly seems to realise how rude he’s being, and apologises; though he still has some friends in Earth Security, he hasn’t dealt significantly with other humans since he accepted the posting to Gholos -- a serene world occupied by a gestalt of pure mental energy, and the only place where Loozly has ever been truly happy.

The Doctor returns to his ready room, where he learns that the terrorists have been driven away from Achilles 4. Mel joins him, but as they speak someone slips a note under the door warning the commander to “beware the pits of Angvia.” What does this mean? Is someone trying to blame Angvia for the murders? Mel, still convinced that Fassbinder is hiding something, decides to search his lab for evidence while the Doctor meets Queen Angvia in the station’s dining sphere. Angvia goes directly to the main course, laughs loudly and boisterously at the Doctor’s nervous small talk, and refuses to discuss petty politics. Tonight is not about war -- it is about love! Before the Doctor can protest, Angvia drags him across the table, smothers him in her more than ample bosom, and professes mad, passionate love for him. And much to his surprise, he realises that he feels the same way about her.

The Doctor finally realises what he’s been missing for all these years, but just as he’s about to surrender to Angvia’s charms, Lieutenant Strindberg contacts him and requests his immediate presence on the command deck. The Doctor is forced to tear himself away from Angvia’s embrace, but promises to return. However, he remains distracted and almost entirely uninterested when Logan’s murder is reported, and Harcourt notes his odd behaviour and realises that it may be her duty to rescue her commander from the Queen’s wanted attentions -- her professional duty, of course. In the meantime, however, she has a post-mortem to conduct.

Mel also notes the Doctor’s strange behaviour, and she’s rather put off by Nicky, who seems almost pleased that the murder gives them reason to stop the contest. Gholos appears to have changed its tune, however, as Loozly passes on its opinion that preparations for the contest are too advanced for them to stop it from going ahead. The results of Harcourt’s tests are inconclusive, and though infuriated by Loozly’s attempt to insinuate that Angvia is responsible for the murder, the Doctor decides to let the contest go ahead. Mel shows little sympathy as the stricken Nicky retreats to his cabin to relax; the pills provided by Eleanor have done nothing to help him. Loozly and Gholos also retreat to prepare for the contest.

Mel drags the Doctor into the ready room and demands to know what’s going on, and the Doctor himself begins to realise that he’s acting bizarrely out of character. There are some things that he simply never does, but for a moment he was about to do one of those things with, of all people, Queen Angvia. The Doctor pulls himself together and considers Logan’s murder properly, and after a moment realises what the motive was. However, he has no proof and thus refuses to tell Mel. Mel sets off in search of the missing Fassbinder, convinced that his disappearance proves that he’s linked to the murders somehow. The Doctor questions Eleanor, who assures him that she’d trust Ivor with her life, and frequently has. Eleanor leaves reluctantly when Queen Angvia arrives, but when Angvia attempts to resume their previous “discussion,” the Doctor -- albeit reluctantly -- rejects her advances. Shocked and astounded, Angvia leaves in tears as the Doctor desperately tries to work out why he’s apparently fallen in love with her.

Lieutenant Strindberg takes the place of Commentator Logan in order to keep the contest going, and does a remarkably poor job of filling in. Meanwhile, Nicky buys roses for Mel to make up for his self-centred behaviour, and Mel accepts his apology and asks for his help in finding Fassbinder. They eventually locate him in the main hall; there are still some empty seats in the back, and Fassbinder is sitting in the dark all by himself. Mel accuses him of falsifying the results of his sensor scan and of killing Commentator Logan, but it gradually sinks in that he’s not listening and is in fact babbling quietly away to himself. Mel and Nicky get him to the sickbay, where Eleanor prepares to run an extensive series of tests to determine what’s wrong -- but the Doctor notices that Fassbinder is gesturing at his neck, and finds puncture marks, revealing that he’s been poisoned. He’s not the killer, but yet another victim. Dying, Fassbinder finally admits the truth to his old friend Eleanor -- all of the technobabble he’s been spouting for years was just nonsense he made up on the spur of the moment, and in truth, he’s been drunk throughout most of their adventures together. Having got this weight off his chest, he prepares to tell them who the murderer is, but unfortunately dies first.

The Doctor orders a full security clampdown, but insists that the contest go ahead as planned. In the meantime, he and Mel return to the ready room to compare notes. Presumably the TARDIS is still out there after all; Fassbinder simply couldn’t work the scanning equipment properly. The Doctor sends Mel to the concert hall to keep an eye on things, and tries to think his way through the tangled mystery. As he does so, Gholos arrives, crackling urgently, and a moment later Loozly catches up to translate his claim that Angvia murdered Fassbinder with an Angvian poison, using her dinner date with the Doctor as an alibi. The Doctor notes Gholos’ greatly agitated state and promises to investigate the warning fully, but as Loozly and Gholos depart, Geri contacts the Doctor to inform him that Angvia has been attacked in her dressing room and knocked unconscious...

The Intergalactic Song Contest is about to begin, and Strindberg is beginning to get the hang of audio commentary, more or less. Nicky is feeling desperately ill, but as he tries to calm himself down, the panic-stricken Geri rushes past him and Mel, revealing that Angvia has been attacked. Mel begins to wonder whether Geri is too good to be true; after all, she’s the one person nobody would suspect. Angvia has been the most obvious suspect, and now that she has been attacked it would seem that Gholos is responsible -- or is that just what some third party wishes them to think? With the reluctant Nicky in tow, Mel follows Geri to a deserted corridor where, in defiance of the Doctor’s orders, Geri uses a subspace communicator to contact home base and assure them that, despite recent difficulties, everything is going to plan. Convinced that Geri is working for the terrorists, Mel tries to restrain her, but as they struggle, Geri hits her head quite sharply on the floor. Perhaps too sharply. It appears that Mel has just killed the arbiter of the Intergalactic Song Contest...

The Doctor realised the truth when the delirious Queen began rambling about political deals between Angvia and Gholos. The “conference” on Achilles 4 was staged as an obvious target for terrorists; in truth, the key delegates have been imprinted in the subconscious minds of Nicky, Queen Angvia, and Gholos, and the real peace conference has been taking place telepathically on Dark Space 8, under their very noses. Geri is not here to mediate the song contest, but the peace conference. The Doctor now knows who the murderer is, and he orders Mel to bring Nicky Newman to the guest lounge. He then returns to sickbay, where Eleanor has just revived Geri using the Doctor’s smelling salts. The Doctor allows the recovering Angvia to perform at the song contest, but orders Eleanor to join the others in the guest lounge -- but before joining her, he has a private chat with Geri.

Due to the earlier protests, the contestants are now singing in alphabetical order. Angvia thus follows the architects of Algol 7, and sings a wailing, off-key martial tune praising her world’s military might. She then sweeps triumphantly into the guest lounge, only to find the other suspects waiting. Gholos crackles, Loozly fumes, and Nicky’s stomach churns nervously as the Doctor and Geri arrive, bearing an odd electronic device which Loozly seems to recognize. It’s time for the denouement.

The Doctor begins by revealing the truth about the peace conference. He then reveals the truth about Eleanor Harcourt, who’s failed to save so many of her patients, failed to revive Angvia, failed to notice that Cyrene and Fassbinder had been poisoned, and failed to respond when Mel asked for “the Doctor’s” opinion earlier, because she isn’t a real doctor at all. Eleanor admits the truth; she’s a stowaway who came to Dark Space 8 in search of adventure, lied about her qualifications, and was, remarkably, accepted at face value. However, she insists that she had nothing to do with the murders, and the Doctor believes her. He thus turns to Nicky Newman, who’s been hovering almost unnoticed in the background all along, sick with stage fright and desperately hoping that the contest will be cancelled. But of course it’s ludicrous to think that Nicky could have committed murder just to avoid having to sing, and after toying with him for a moment the Doctor admits that Nicky is innocent -- and perhaps now he’ll realise just how trivial his fears really are.

Having dealt with the red herrings, the Doctor is now ready to reveal the killer’s identity. The Commander’s shuttle was destroyed with an Angvian scatter bomb, Cyrene and Fassbinder were killed with Angvian poisons, and Angvia tried to seduce the Doctor using the pheromonal glands in her armpits. Geri tried to warn him earlier by slipping him a note to “beware the pits of Angvia.” Angvia is thus the obvious suspect -- but, of course, that’s far too obvious. When the Doctor orders Geri to switch on the device they brought in with them, Gholos is finally able to speak freely -- and the voice of Commentator Logan accuses Loozly of murder.

A fierce Gholosian nationalist, Loozly is bitterly opposed to making peace with Angvia, and after leaning the truth about the conference from his friends in Earth Security, he arranged to be assigned as escort to the contestant and set about trying to sabotage the peace conference by any means necessary. His attempts to frame Angvia for the murders failed, however, as the station’s doctor and science officer were too incompetent to notice the obvious clues he’d planted. This is why Gholos “attacked” Mel earlier; it was in fact trying to warn her about Loozly, but nobody else could understand what it was saying. Loozly has since forced Gholos to behave using the device he claimed was monitoring its health. However, when he heard Logan announce that he was building a translator, he had to kill the commentator to prevent Gholos from getting its message out -- and presumably Fassbinder, who wasn’t entirely incompetent after all, worked out the truth on his own.

Loozly insists that he had to act to preserve the serene, perfect gestalt from corruption by lesser beings. He attacks the security guards and takes Angvia hostage, and reveals that he’s holding the detonator for a bomb capable of destroying the entire station. However, as Loozly prepares to retreat, Gholos strikes him down with the “blue sting of Gholos,” avenging itself and saving Angvia’s life in the process. Angvia, shaken, realises that her people may be able to make peace with Gholos after all. Nicky prepares to go on stage, still nervous but having learned his lesson. Gholos and Geri depart to resume their respective duties, and the Doctor, somewhat sadly, has Eleanor taken away to face trial for impersonating a doctor. It appears that everything has been wrapped up nicely, and it’s time for him and Mel to take their leave and set off on another exciting adventure...

Except that it all seems to have been wrapped up a bit too easily, and indeed, when security searches Loozly’s cabin they can find no trace of the bomb with which he threatened to destroy the station. How could he have smuggled such a powerful explosive on board? Angvia casually remarks that an Angvian personal destructor would be the perfect weapon; it is a fragment of black star matter coated in a pill, which attaches itself to the victim’s digestive tract when swallowed. When the victim becomes agitated, the pill dissolves and the black star fragment explodes with the force of 50 scatter bombs. Mel works it out immediately: Loozly was using Angvian weapons to pin the blame on them; while on the shuttle to Dark Space 8, he gave Nicky a “headache” pill -- and Nicky, already suffering from a terrible case of stage fright, is about to go on stage in front of millions of viewers...

As the crowds in the arena sing the Earth national anthem, I Will Survive, Nicky Newman prepares to go on, his stomach churning with tension. The Doctor and Mel catch up to him just before he steps out on stage, and, improvising wildly, the Doctor claims that he’s arranged to go on in his place. Nicky doesn’t know whether to be angry or not about the Doctor stealing his thunder, but when Mel suggests that they go back to his cabin for a nice relaxing chat, Nicky works out why she wants to get him alone -- or so he thinks. Realising that Nicky is getting excited again in an entirely different way, Mel gives up and thumps him, knocking him out and dragging him to the sickbay. Meanwhile, the Doctor’s sudden appearance on stage causes some confusion amongst the crowds who were expecting Nicky Newman, but when he pulls out his spoons and begins tapping along to the techno pop beat, they soon get into the swing, and the Doctor steals the show.

As soon as his performance is over, the Doctor fetches Eleanor; despite her lack of official qualifications, years of conducting operations have given her enough practical experience in space medicine that she’s the only one on the station qualified enough to remove the bomb from Nicky. Eleanor pulls herself together and gets through the operation, saving Nicky’s life, and as the Earth delegate’s telepathic imprint is incapacitated, the Doctor steps in and helps Geri to arbitrate the peace conference -- and with his guidance, both sides sue for peace, ending centuries of war.