Jamie wakes up and finds Nurse Muir watching over him. He remembers her bandaging his head when he was first brought in, but that seems like days ago. He was told he was struck by lightning while out on the moors, but that doesn‘t make sense as it was a bright clear day. The men who found him said the heather around him was dotted with flame and his head was smoking. Oddly, the lightning seems to have cleared his head and it’s helped him to remember travelling in the TARDIS with the Doctor. He wants to tell the nurse about Mindy Voir and Helicon Prime…

The Doctor had got so carried away with his tinkering that he didn’t even notice when the TARDIS landed. He’d been trying to put back together some equipment that he’d taken apart earlier, but it didn’t look the same when he finished and he ended up kicking some of the pieces away while he thought Jamie wasn’t watching. He opened the scanner to reveal huge leaves and ferns. Victoria was still away on her graphology studies, so he told Jamie they should take the opportunity to enjoy some fresh air and a nature ramble - but when he opened the doors, they heard music and the sound of conversation.

Outside they found the TARDIS had landed behind some large potted plants. They appeared to be in the corner of a high class restaurant, but it didn’t look like Earth. The waiters appeared humanoid, but most of the guests were alien, including a woman sitting at a nearby table with green skin, reptile eyes and a forked tongue. Outside the restaurant was a grand staircase leading down into a bustling hallway with a fountain in the centre. The Doctor spotted a group of cat-like creatures walking upright and told Jamie they must have landed a long way from his side of the Universe. They noticed the water in the fountain was flowing upwards and the Doctor said they must be somewhere with sympathetic gravity.

Several people in uniforms were handing things out to the passing guests and the Doctor and Jamie were both given pass keys indicating they were on Helicon Prime, a luxury resort where people came to be pampered in sumptuous surroundings. It’s one of the most exclusive holiday destinations in the Universe and it’s always booked up decades in advance. An imposing figure in flowing robes swept urgently down the stairs and the Doctor told Jamie he was a Galactic Ambassador. Other important looking people rushed over to join him and they all headed off down a corridor, followed by a shoal of brightly coloured fish and some of the waiters. Clearly something was going on, so the Doctor decided to investigate.

They soon found a crowd of people gathered around the doors of a drawing room, trying to see what was going on inside. One of the staff called for a doctor, so the Doctor quickly stepped forward and pushed his way passed the Ambassador. Mindy Voir, an attractive young woman with silver hair, told Jamie she’d overheard one of the staff say someone had been found dead, which was unusual as nothing bad was ever supposed to happen on Helicon Prime. The Doctor joined them and revealed that one of the guests had died, but no one knew why. The Doctor immediately brightened when he saw Mindy and shook her hand enthusiastically, claiming to be one of her greatest fans. Mindy was a singer and the Doctor said he often played her recordings - although Jamie couldn’t remember when. She said she was trained by her father, who was a pioneer of sonic sculpting, and he developed special techniques to expand her voice to its greatest potential and she was now the only human with a ten-octave range. The Doctor produced a piece of frayed string from his pocket and asked Mindy for a sonic signature, explaining to Jamie that she was capable of tying knots simply by using vocal sound vibrations. Mindy showed Jamie her pendant, which was shaped like a knot, and when he held it, he could feel the whisper of a tune.

The Doctor decided they should stay on Helicon Prime for a while. Before long, he’d finished reading his fourth book, tried every machine in the amusement arcade, and taught Jamie how to play table tennis - although he stopped as soon as Jamie got the knack of it - then they found themselves relaxing on the bright-red shore of a make-believe lagoon. Jamie asked if they were keeping an eye on a suspect, but the Doctor said he wasn‘t even sure anything untoward was going on. Jamie accidentally knocked over a bowl of dates and little whirpools immediately appeared in the sand and swallowed up the mess. Jamie started getting bored and thought they should be off somewhere battling Daleks or chasing Yeti, not being mollycoddled on a beach, but the Doctor didn’t think they were wasting their time. Why else would the Ambassador’s secretary be taking such an interest in them? Jamie realised they were being watched and the Doctor revealed that for some time now they’d been followed everywhere they went. From what the Doctor overheard Ambassador Dromeo saying earlier, the guest who died was a mining speculator called Galax. There’s a lot of money to be made in that business and in the Doctor’s experience, money always brings out the worst in people.

Jamie decided to go for a walk on his own and discovered Helicon Prime was designed like a honeycomb so that wherever you were, it was easy to find your way out again. He saw a short squat creature sitting by the fountain. It had a mouth filled with dangerous looking teeth, but was wearing knee-breeches and a bow tie, and it kept checking a watch in its waistcoat pocket. The creature introduced itself as the Gorgol Chime and said he’d arranged to meet someone here for dinner. Just then, a charming young lady with long golden hair appeared and the couple went off together - even though the Gorgol only came up to her waist.

Next, Jamie encountered a figure composed entirely of glass who told him Helicon Prime used to be a retirement destination in the Parnassas Cluster, but the languor and inertia here tended to make older couples realise how much they actually disliked each other. He said an undercurrent of violence developed, so the entire place was moved to this sector of space where it could benefit from the soothing effects of the Golden Section. The glass man, whose name was Romea, knew that Jamie had come here with the Doctor and warned him to be careful as Ambassador Dromeo had taken an interest in them both.

Over dinner, Jamie told the Doctor about Romea’s warning, but he didn’t seem particularly bothered. They checked the menu and the Doctor advised Jamie not to order anything without checking first as some of the food could do a lot of damage to the human system. On the other side of the restaurant, Jamie spotted Romea apparently eating blobs of light, but the man didn’t look very well. He started twitching and then collapsed into the next table. Cracks appeared in his body and then he completely exploded, showering the other diners with clouds of crystal dust. The Doctor asked everyone to step back and he examined some of the blobs of light that Romea had been eating. He told Jamie they were formed from a volatile wavelength, so in a manner of speaking, Romea had been poisoned. A waiter told the Doctor that Ambassador Dromeo, who resided in his suite on an exclusive reserved floor of the resort, had been informed of the latest incident.

The Doctor told Jamie he wanted to find out what killed Galax. Helicon Prime was in the Golden Section, a peaceful harmonious area of space that provided a unique oasis of calm, contentment and good feeling. It should have been impossible to feel anger or aggression here and only a few lifeforms were immune to its influence. Jamie suspected Ambassador Dromeo might be employing such a species. The Doctor wanted to make sure Dromeo found out he was planning to examine Galax again because he’d probably want to be present and it would give Jamie the chance to sneak up to his private suite and look around.

Jamie found himself waiting by the lifts and as soon as the Ambassador started coming down from his floor, the Doctor used his sonic screwdriver to override the security locks on the other lift so that Jamie could go up. The lift stopped at Ambassador Dromeo’s floor and Jamie stepped out onto a deserted hallway. Down one corridor he found several empty bedrooms and a locked door, but as he headed back, he heard the lift coming back up again. Jamie quickly hid behind a fountain, hoping he could escape without being seen, but when the lift doors opened he was surprised to see Mindy Voir step out.

Mindy admitted that she’d followed Jamie as she was curious to know why he was searching the Ambassador’s rooms. Jamie said they suspected Dromeo might be involved in the two deaths and suggested she leave immediately as it might be dangerous, but Mindy said he might need her help as she’d been here once before when the Ambassador invited her to an exclusive reception party. She led the way down another corridor and they entered a large room. Through a huge window looking out to space, Jamie could see the Golden Section, the effects of which made everything in the room sparkle with golden light. It reminded Jamie of a mist rolling across the glen back home and before long he was feeling very calm.

Jamie and Mindy ducked into an alcove containing a communication device and drew the curtain across. They watched as Dromeo entered with his secretary and two guests, one named Erlon, who wore a space uniform and the other, Rathan, who had feathers on his head and hands. The group retired to the drawing room area and began discussing their plans. The three men represented the last members of the Fennus rescue mission. They believed they were entitled to the colony’s treasure, but its exact location was unknown to them and they suspected it may have been in Romea’s possession. Suddenly both Erlon and Rathan began spluttering and they dropped their glasses before crashing to the floor, dead. Dromeo calmly summoned his secretary and gave orders for a personal shuttle to be prepared. The secretary headed for the communications alcove and Jamie was convinced they were about to be discovered, but Mindy skilfully threw her voice to make it sound like there were intruders in the next room. Dromeo and the secretary rushed over to investigate and while their backs were turned, Jamie and Mindy were able to make their escape.

Jamie tracked down the Doctor outside the medical centre and learned that Helicon Prime was being drawn out of the Golden Section, away from its pacifying influence. Unfortunately Ambassador Dromeo had used his authority to place a banning order on anyone examining Galax’s body. Jamie revealed that he and Mindy had just seen the Ambassador poison two of his guests. The Doctor said Fennus was a colony very far away, but it was abandoned a long time ago. For a while it was one of the more successful of the pioneering Frontier Colonies, but the planet proved to be unstable. The Doctor had never heard of a rescue mission and had always believed the colonists all perished. Jamie assumed Dromeo was getting rid of all his partners so he could keep the treasure for himself, so he suggested dropping a hint to the Ambassador to make him think they knew where the treasure was, then they might be able to trick him into confessing to the murders.

The drift away from the Golden Section was starting to have an effect on the guests and some people had to be separated after an argument broke out. The Doctor invited Mindy to join him and Jamie in the restaurant, where he used the opportunity to get her to sign one of the albums from his collection. He took a flat star-shaped crystal from his pocket and she sang a single note which rose in pitch until it was impossible for anyone to actually hear it. The crystal began to tremble and her signature appeared on it, together with a little kiss. The Doctor was delighted and gave her a yo-yo in return, but then he pointed out that Jamie was the only one without a gift, so Mindy agreed to the Doctor’s suggestion that she give him the knot-shaped pendant from around her neck.

A waiter arrived with a tray which he said came with the Ambassador‘s compliments. On the tray were three of the most delicate flowers they’d ever seen. Mindy explained that they were Asphadills and said they were intoxicatingly pleasant, but she warned that they take ages to eat. Jamie tried to pick one up, but it shimmered around his fingers as if it was made of smoke. The Doctor explained that the flowers are so fragile and delicate they’re on the very edge of our reality, almost as if they’re about to disappear entirely, and it requires infinite patience to keep them in your perception long enough to eat them. Ambassador Dromeo and his secretary arrived and took a seat by the door. Jamie thought Dromeo was acting as if he owned the place and the Doctor realised he probably did and it would explain why the last members of the Fennus tontine met here. Suddenly an argument broke out between one of the customers, a huge hairy creature, and one of the waiters. Realising the effect of the Golden Section was weakening, the Doctor decided to put his plan into action immediately. ..

The Doctor asked Mindy to take the stage and join the band in giving an impromptu concert and the lounge quickly filled with people wanting to hear her perform some of her best known songs. The Doctor then asked Jamie to keep an eye on the Ambassador and follow him if he left the room. Not long after that, the Ambassador did indeed leave and Jamie was about to go after him when he was distracted by the sight of the hairy creature eating some of the brightly coloured fish. Helicon Prime was definitely breaking down and violence was resurfacing from the smothering calm of before. Jamie caught up with Dromeo just in time to see him enter another room with his secretary. Jamie saw them ransack the room, but they obviously didn’t find what they were looking for as they did the same to another three rooms.

The Ambassador became increasingly angry with each failed search. He and his secretary reached another room, then they hid in an alcove as the door opened unexpectedly and the Doctor emerged, scurrying away down the corridor with something under his arm. The secretary stepped out and pointed a gun at the Doctor’s back, so Jamie hurled his pass key directly into the back of the man’s head, deflecting his shot. As the Ambassador turned his attention to Jamie, they were interrupted by the sound of an explosion on one of the upper floors. The Doctor said Helicon Prime was starting to collapse under the terrible pressures caused by moving it from the protection of the Golden Section.

The Ambassador was alarmed, but knew he’d be leaving as soon as he located the Fennus treasure. The corridor continued to lurch and the Doctor asked Dromeo whether all the death and destruction was worth just a few precious metals or minerals. The Ambassador realised the Doctor didn’t even know what the treasure was, but the Doctor countered this by saying he knew how many eyes a Nessus should have. Dromeo realised he meant the treasure was hidden in the Nessus head mounted on the wall - so it had been quite literally staring him in the face all along.

Dromeo revealed that Fennus was a gathering of some of the most brilliant minds for decades, a community thriving on its own intellect. The mining techniques they developed were amazingly advanced and it was only the planet itself that was unstable. By the time the rescue mission reached them, the planet was disintegrating and it was too late to save the people. The only thing that could be reached was their data banks and the contents of the colonists’ brilliant minds. The Ambassador offered to share half the Fennus treasure with the Doctor, but Jamie said it didn’t matter how many clever ideas were on offer if you’re about to be smashed to smithereens.

Helicon Prime lurched again and the Doctor said the energy links would fail soon, making Dromeo’s escape impossible. The floor started to buckle and sparks spat out from the ceiling. The secretary panicked and ran for his life, leaving the Ambassador alone with the Doctor and Jamie. The Doctor said he’d decided to hand over the data banks to the descendents of the original colonists. Dromeo moved in to attack him, so Jamie leapt on his back and spun him around. The Ambassador looked at them with murderous rage, then as smoke started to pour from the walls, he too turned and fled. Jamie was convinced the entire resort was about to blow up, but the Doctor said that if he could get to the TARDIS in time, he might be able to place Helicon Prime back into its proper orbit.

Jamie finishes his story and is pleased to see that Nurse Muir is still with him. He knows she probably thinks he‘s mad after hearing his tale, but the memories are starting to fade already, like a dream that you struggle to remember in the morning. Jamie can’t understand how the Doctor was planning to return the data banks to the descendents as the TARDIS had a mind of its own, but he can’t remember what happened next anyway. The nurse tells him they never made that journey and as he starts to recognise her voice, she tells him her name is Nurse Voir, nor Muir, and he must have misheard her.

Jamie asks Mindy what she’s doing here. She tells him it took a long time to unravel the Doctor’s clever scheme, but she eventually realised his story about the Nessus head was just a bluff to confuse the Ambassador. She apologises for injuring Jamie when she landed, although for her it turned out to be fortuitous. She knows the Doctor kept Jamie as much in the dark as everyone else when it came to his plan, so she tells him that after the Doctor shunted Helicon Prime back into the Golden Section, he disappeared with the Fennus treasure. She orders Jamie to hand the treasure over or else she’ll claw his mind apart to find it. She reveals that her father was part of the Fennus tontine too and it was his expertise that preserved the collective memory of the colonists, but he died and never told her where it was hidden. All this time she thought Romea had it, which is why she killed him, but now she realises Jamie must have it.

As Jamie struggles off the bed, he hears Mindy start to sing a low note which rattles the walls. The pitch of the note lowers so that instead of hearing it, Jamie can actually feel it throughout his body. It begins to hurt and he knows Mindy is killing him. He sinks to his knees and the pendant swings free from his neck. He suddenly remembers his gift from Helicon Prime and starts to unwind the knot. He hears voices, crying out for release and the more he unwinds the knot, the clearer the voices become. Mindy orders him to stop, but the room is now filled with confused voices. Mindy tries to grab him just as a burst of pure sound knocks him backwards.