The TARDIS materialises on Lebenswelt, one of the richest worlds in the galaxy and one of the furthest out. The planet’s mineral resouces have been sold to the Galactibanks, making the population fabulously wealthy, and nobody is willing to travel out this far just to work in public service. Thus, Lebenswelt is home to an eternal hedonistic party -- and nothing ever gets fixed or cleaned up. The streets are full of garbage, and flocks of carnivorous bats tear each other apart in mid-air between the skyscrapers. Fitz is in his element, Anji just wants to go, and the Doctor has a mystery to solve; when the TARDIS printed out a map of the city, it highlighted Das Museum der Verriegelungen, the “Museum of Locks,” and the Doctor wants to know why. He takes Anji and Fitz to the top of a spectacularly high observation tower to get a good look at the city, but once there he has a sudden mental spasm and nearly falls over the edge. He wakes with the feeling that something dangerous is coming, and that the “Book of the Still,” an exhibit in the Museum, is vitally important. He thus makes a spectacular attempt to steal the Book by free-falling from the edge of the atmosphere while protected by a stasis bubble -- but fails, and is arrested and sentenced to twenty years in prison.

Anji looks into all possible recourses, but can’t find any way to release the Doctor legally. Fitz, convinced that the Doctor will escape on his own, decides to spend his time filling in the blanks about Lebenswelt in the TARDIS data bank by going to as many parties as possible. He eventually notices an advertisement offering the chance to become another person for a day and get paid for it; intrigued, he answers the ad to find himself in a back-alley escort agency run by the seedy Darlow, his enforcer Gimcrack and the scientist Svadhisthana. Before he quite realises what he’s gotten himself into, Fitz is injected with fast-chain memory acids, and under Svadhisthana’s guidance, experiences a fantasy in which he, the swashbuckling Fitzgerald, rescues his lady love Carmodi Litian from the evil Duke Doctori and Lady Anjilina. Fitz and Carmodi rush out into the streets of Lebenswelt, wildly and effervescently in love -- but soon afterwards, Darlow loses track of them and discovers that Carmodi’s credit transfer has drained money out of his own account. Infuriated, he sends Gimcrack after Fitz and Carmodi while he scans their real memories for clues. The unlicensed application of memory acids is illegal, and IntroInductions will have to pack up and move out -- but before he leaves the planet, Darlow wants revenge.

The Doctor has been imprisoned with young academic Rhian Salmond, who studies time-travelling cultures and who also attempted to steal the Book of the Still. The Doctor doesn’t actually know what the Book is, and Rhian explains that it exists in all times and places, enabling stranded time travellers to write their names and locations inside so they can be rescued. Das Museum der Verriegelungen is actually a museum of security measures, and the obscenely wealthy owner purchased the Book just as something to be guarded by the actual exhibits. Now, hundreds of time travellers are imprisoned on Lebenswelt for trying to steal the Book, some so they could write their names in it, some so they could find people who need rescuing, and some who wished to release it back into circulation and make the whole process that much easier.

The Doctor and Rhian are out in the exercise yard when a sentinel suddenly falls from the sky, striking and destroying one of the Warderbots monitoring their behaviour. The prison governor accuses the Doctor of somehow causing the momentary power failure, and when another power failure strikes, he orders his guards to execute the Doctor. Their guns fail to work, however, and the Doctor escapes, dragging Rhian along with him. They escape from the prison before the power comes back on, much to Rhian’s despair; with good behaviour and an appeal, she could have been out in months, but now she’s a fugitive from justice. Nevertheless, she still wants the Book of the Still, and she thus accompanies the Doctor back out into the city to rejoin his companions and make another attempt to steal the Book.

Anji becomes worried when Fitz fails to return, and tracks him down to IntroInductions, where Darlow recognises her from Fitz’s memories and tries to capture her. She escapes when a power failure causes Darlow’s artificial legs to switch off. Meanwhile, Carmodi convinces Fitz to leave the planet with her and get married, and he’s so deeply in love with her that he agrees to do so without question. She isn’t only on the run from Darlow, however -- she knows what the power failures signify, and this means that soon Lebenswelt will be destroyed. On their way to the spaceport, Carmodi hits her head and suffers from a fit; Fitz doesn’t understand what she’s talking about, but picks up that she’s concerned about the Book of the Still. He thus finds his way to the Museum, and thanks to the power failures, walks straight past the security devices and steals the Book of the Still.

The power failures cause a hoverbus to crash, and despite the risk of discovery and arrest, the Doctor insists upon stopping to help the victims. The watching crowd is then attacked by the savage bats, which have felt the city’s growing fear and have realised that the people are now vulnerable. The Doctor and Rhian help get the people to safety, but as they leave, the Doctor suffers another fit and senses something truly dangerous approaching. He also senses that the Book of the Still is now at the docks, and sends Rhian to collect Anji while he investigates. Darlow, Gimcrack and Svadhisthana are also at the spaceport, preparing to leave, when their DNA sniffer starts to work again and picks up Fitz’s presence nearby. Gimcrack fails to capture Fitz before he and Carmodi take off in a stolen shuttle -- but he does find and capture the Doctor, recognising him from Fitz’s memory scans.

Fitz is beginning to realise that Carmodi’s behaviour is rather odd, but he has little time to question her, for the Unnoticed are coming; they have trained a Wave Interruptor on the planet to shut down all signals and prevent the people of Lebenswelt from escaping, and Carmodi and Fitz can only escape by locating the Resonance Corridor which the Unnoticed will use to pass through the Wave Interruption field and fly out in the opposite direction. It’s a dangerous manouevre, which involves passing so close to the Unnoticed’s ship that they crash into the hull -- but Carmodi succeeds, escaping from Lebenswelt as the Unnoticed move in to destroy it.

Anji and Rhian find Darlow and his associates torturing the Doctor, and alert docks security, apparently forcing Darlow to release the Doctor and flee. They then drag the exhausted Doctor back to the TARDIS -- but just as they arrive, the Unnoticed’s ship enters the atmosphere, and the sonic boom knocks the TARDIS over onto its doors. The burnt-black ship hangs in mid-air all night, doing nothing, and while the Doctor slowly recovers, the people of the city begin to panic and run amok. Once fully recovered, the Doctor takes Anji and Rhian to the observation tower to get a good look at the ship. The Mayor of Lebenswelt arrives with his bodyguards, but is unwilling to take advice from the Doctor -- until a triad of three-metre-high aliens hidden under black trenchcoats materialise at the end of the platform and order him to surrender the Book of the Still or see his people die horribly.

Fearing the worst, the Doctor orders Anji to deal with the TARDIS in case they need to get into it in a hurry. She returns to the streets, whips up an angry mob of looters and leads them to the park, where they topple the TARDIS back over onto its side. She enters and locks the doors behind her, keeping the mob out. Once they get bored and drift away, she emerges -- but runs into Darlow and his associates, and is taken prisoner.

One of the trenchcoated aliens pulls an emaciated humanoid with suppurating skin from beneath its trenchcoat. She detects the scent of time travel on the Doctor, and the aliens decide he must die. However, when he reveals that the Book is no longer on Lebenswelt and the emaciated humanoid confirms this, the infuriated aliens toss the humanoid over the edge of the platform, transport a world-killer bomb to the platform, return to their ship and depart. The Doctor, realising that he can’t defuse the bomb, leaps onto the top of the tower’s lift and kicks the brakes, sliding down the lift shaft to the bottom. Fortunately for Lebenswelt, he reaches the TARDIS just in time and materialises it around the bomb, muffling the explosion and saving the planet. The TARDIS will need time to recover; fortunately, it recently generated a Minus Room which refracts reality around itself, and the Doctor hid inside it and survived. The grateful Mayor allows him to access the docks’ security records, which confirm that Fitz and Carmodi have left the plaent -- as has Anji. The only planet within the range of Carmodi’s shuttle is Antimasque, and the Mayor allows the Doctor and Rhian to book the earliest flight out. The trip takes over two weeks, and the Doctor needs all that time to recover; at one point he wakes from a nightmare of the universe unravelling and nearly strangles Rhian to death before he realises what he’s doing.

On Antimasque, Fitz is finally starting to realise that his memories contradict each other, and that Carmodi is just as “attracted” to the Book of the Still as she is to him. Carmodi finally admits that, through no fault of her own, she has become addicted to the energies which build up in the bodies of time travellers. When Fitz visited IntroInductions she realised that she could alter his memories to ensure that he stayed with her of his own accord, “rent” him, and then steal him. Fitz is sickened to realise that his lover regards him only as a fix, and that the love he feels for her is based on false memories -- and that, even knowing this, he still loves her.

The Doctor tracks down a hotel on Antimasque with “Fred Astaire” and “Ginger Rogers” booked in. Recognising Fitz’s style, he takes Rhian to investigate -- but Darlow and his associates have beaten him to it. Having studied Carmodi’s memories, Darlow knows that the Book of the Still is important to her, and he thus intends to steal it and make her suffer before he kills her. He thus injects Anji with fast-chain memory acids so that she believes she’s living out a role in a Bollywood movie (complete with singing, dancing and sudden changes of location). However, Svadhisthana rushes the process, and Anji is resisting the false memories -- and thus, although she steals the Book from Carmodi’s hotel room, she then dances away into a nearby masqued ball, which she believes is her own surprise wedding. Darlow and his team must follow her.

Carmodi is desperate to recover the Book, which will enable her to track down time travellers so she is never short of her fix again. As a time-sensitive she is constantly nauseous, due to the feeling of Time washing through her; only when she is with a time traveller does she feel momentarily at peace. Fitz agrees to help her find the Book, and they go to the ball, as do the Doctor and Rhian. Rhian is amused to find that the Doctor doesn’t know how to dance, and that this fact genuinely upsets him. However, just as the various interested parties are about to converge, the Unnoticed blast their way into the ballroom and begin shooting. The Doctor spots Carmodi heading for the Unnoticed and makes a beeline for her, presumably to save her life, but he is knocked away by one of the Unnoticed. By the time he recovers, it’s too late; Darlow and his associates have recaptured Anji and the Book of the Still; Carmodi has gone with the Unnoticed, claiming to be one of their “canaries”, and Fitz has gone with her; and the Unnoticed have departed, planting another world-killer bomb in the ballroom.

The Doctor explains the dire situation to the authorities. Without the TARDIS, which is still recuperating on Lebenswelt, it appears that Antimasque is doomed... until the Doctor notices that the Unnoticed’s ship is still present, and realises that they are being affected by their own Wave Interruptor. They must wait for the plaent to orbit back around to the Resonance Corridor, which gives the Doctor just less than a day to save the planet. He thus gathers an orchestra together and has them play a carefully modulated series of notes which cancel out the Wave Interruption signal. He records the note onto a floppyscreen, and copies it onto more floppyscreens; with these screens, constantly playing the interference signal, the people of the pleasure zone can get their ships working again and escape from the planet. There’s still an ecosystem full of lfie to save, and the Doctor plans to take one of the floppyscreens to the bomb in the hope that the interference signal will prevent it from going off. Before he can do so, however, Gimcrack knocks out him and Rhian and takes their floppyscreen, as Darlow intends to evacuate and leave them to die.

The Resonance Corridor finally reaches this side of the plaent and the Unnoticed go, triggering the bomb as they go. Realising they are doomed, Rhian teaches the Doctor how to dance. Anji, however, has overpowered Darlow and is holding him at gunpoint, still living out her Bollywood fantasy and believing Darlow to be her Evil Uncle Abdul. To distract her, Darlow teleports the Doctor and Rhian out of the ballroom, but a standoff ensues when the Doctor demands that Darlow hand over the floppyscreen, the only one remaining, so he can try to save the planet. In the confusion, however, Rhian gets hold of the Book of the Still, and finds an entry which changes everything. It’s not the entry written by her father, the reason she tried to steal the Book in the first place -- it’s the entry which she herself will write in the future, proving she will survive these events and get captured by the Unnoticed. As Rhian is predestined to live, the Doctor can’t risk her dying on Antimasque, and thus reluctantly allows Darlow to use the floppyscreen to escape, even though this means the bomb goes off and Antimasque is destroyed.

Carmodi is furious with Fitz for following her, and furious with herself for not realising how much he loved her. The Unnoticed have taken them to their home, a vast city of tents woven from the fabric of reality itself, which they can move if threatened with discovery. In their natural form the Unnoticed are floating gasbags; their interior organs are exposed and their stomach acids slosh about, occasionally dripping onto the skins of their “canaries”. The Unnoticed were created by a temporal anomaly, and interaction with the rest of the Universe could cause their timeline to collapse; thus, they have bred time-sensitive humanoids in order to alert them to the presence of time travellers, and whenever they are forced to interact with another world they destroy it completely to leave no evidence of their existence. Carmodi used to be a Sensitive until she could bear it no longer and deliberately tried to get the Unnoticed to kill her; however, she survived and escaped into the Universe. Her sensitivity to Time left her addicted to time travellers; however, she’s learned to appreciate life, which is why she returned here rather than stay on Antimasque to die. But the Unnoticed were never after her; they were after the Book of the Still, which contains an entry about the Tent City, threatening the Unnoticed with discovery.

Realising just how upset the Doctor is by failing to save Antimasque, Rhian tells him about her father, who worked for TimeCorp until an accident caused him to become lost in Time. He never returned, and Rhian thus developed her interest in non-linear anthropology, hoping one day to find him. Anji recovers her memories, and once she realises what was done to her the Doctor is forced to lower a bulkhead to save Darlow from her. He then reveals that Rhian’s entry in the Book directs them to the Tent City, which is currently in the photosphere of Earth’s sun. As the Book exists in all times and places, the Doctor theorises that its pages must be made from the quantum fabric of reality, and he tears them out of the Book and sticks them together to create a giant cube of “paper”. Svadhisthana panics when he realises what the Doctor intends to do, and Gimcrack knocks him out and drags him into the cube with everybody else. The Doctor seals up the cube, which is thus the only thing to survive when the ship flies into the sun and is destroyed. Using the floppyscreen to guide him, the Doctor has everybody shift around the inside of the cube to control its flight, gliding through the photosphere towards Tent City.

The Unnoticed question Fitz and have the Sensitives scan him, and eventually conclude that he is not responsible for the accident which created them; thus, it is safe for them to kill him. Before they can do so, however, they discover that Lebenswelt still exists, and flee in panic to the docking bays. Fitz is left alone with Carmodi, who has shed her prostheses and looks like all of the other emaciated humanoids who serve the Unnoticed. She no longer looks like the woman Fitz was programmed to love, but he stays by her side anyway as she explains that the Unnoticed are preparing to collapse the Tent City and flee; since Lebenswelt was not destroyed there is evidence of their existence in the Universe, and they can be found.

Svadhisthana awakens, realises where he is, and tries to kill the Doctor in his panic. Rhian is forced to untie Gimcrack so he can subdue Svadhisthana. The cube then hits the side of Tent City, and the Doctor finds a gap in the wall, enabling them to enter. The hole seals up behind them as the air differential sucks the pages of the Book into the city, scattering them through the corridor. The Doctor sets off to find Fitz and Carmodi, but Darlow pulls a gun on Anji and Rhian, ordering them collect the scattered pages; he intends to use the Book to locate stranded time travellers and either blackmail them or sell their identities to governments without time-travel ability. Anji and Rhian trick and overpower him and flee, pursued by Darlow, Gimcrack, and the now quite mad Svadhisthana.

Carmodi believes that they’re trapped and doomed until she senses the Doctor’s presence in the Tent City. She sensed him on Lebenswelt, but mistook Fitz for the man she was sensing -- a man who carries such a powerful charge of time energy that Carmodi is sure he will give her the stillness she seeks. As she explains this to Fitz, his memories of the Doctor and the TARDIS return at last. He accompanies her to the docking bay, where the Unnoticed are evacuating onto their black ship, just as all of the other interested parties arrive -- but when the Doctor sees Carmodi he unexpectedly tries to strangle her to death, just as he nearly did to Rhian on the journey to Antimasque. While he was in the warehouse on Lebenswelt, Svadhisthana planted a Mindbomb in his brain, programming him to seek out Carmodi and kill her. However, when he and Carmodi touch, the energy discharge liquefies Time to ripple out around them, sending ripples throughout the Tent City and its occupants...

The Doctor realises what he’s doing and gets Fitz to reach through the ripples of Time, into his brain, and pull out the Mindbomb. Time snaps back into place, and the Doctor confronts the confused Unnoticed, demanding answers. Rhian enters the Unnoticed’s ship, desperate to rescue her future self, but the Doctor stops them from killing her, claiming that this will create a temporal paradox. He sends Anji after Rhian to ensure her safety; Carmodi also tries to drag Fitz into the ship with her, but his memories fully return and he realises that he owes his loyalty to the Doctor, not her. Inside the ship, Anji sees Rhian pass through a hatchway -- and then come flying out moments later, cast out by a discharge of temporal energy. Rhian doesn’t explain what happened, but warns Anji that they must escape from the ship at once.

The Unnoticed explain to the Doctor that they are the product of a time anomaly, but don’t know the details of their creation. They discovered the truth when they crossed the wrong timeline and were nearly erased from existence, and ever since then they have hidden from the Universe, refusing even to examine their own past for fear of destroying themselves. Before the Doctor can learn more, Darlow, Gimcrack and Svadhisthana arrive -- but they were too close together when Time went soft, and when it snapped back to normal their bodies were fused togehter into one monstrous organism. The creature attempts to shoot the Doctor, but Fitz intervenes and the Doctor kicks the gun out of its reach. Rhian and Anji then burst out of the ship with Carmodi just as it implodes, vanishing entirely from existence.

Rhian claims to have met her father, and tells the Unnoticed that they must destroy themselves today to cause the time anomaly which creates them. Their timeline is a closed loop in which the beginning is also the end. Carmodi, as a time-sensitive within the closed circuit, built up a potential charge which was released when the time-travelling Doctor contacted her; this discharge caused the elongated moment of Time which fused Darlow and his associates together, and if they touch one of the Unnoticed, the energy release will blast the fused creature back in Time, where it will eventually evolve into the Unnoticed race. The Doctor realises that the blackouts and spasms he suffered earlier, which caused him to channel the Unnoticed’s desire to acquire the Book of the Still, were caused by his entry into a closed temporal circuit; his unique relationship to Time has left him sensitive to such things. The TARDIS showed him Das Museum der Verriegelungen as a warning to stay away from it, and created the Minus Room so he could use it to escape from the predestination bubble. The Doctor refuses to participate any further in a predestined sequence of events which involves the destruction of worlds -- but before he realises what’s happening, Darlow grabs one of the Unnoticed, completing the circuit purely out of spite.

As Time folds up around them, the Doctor grabs the Book of the Still and forces everybody to hold onto it. As he’d hoped, it transports itself back to its last safe location -- the secure room in the museum on Lebenswelt. However, they lose Rhian during their passage through the Vortex. Carmodi is infuriated, for when she touched the Doctor all of the temporal potential in her body shorted out, and by taking the Book out of the closed circuit the Doctor has robbed her of the still point she’s been looking for. Carmodi takes the Book, threatening to use it to track down the Doctor’s friends and kill them if he ever comes near her again.

The Doctor lets her go and returns to the TARDIS with Fitz and Anji, realising that Rhian has fulfilled her predestined actions and let go of the Book deliberately, in order to be cast out of the Vortex in the Unnoticed’s ship two days before its destruction. However, when he tries to rescue her he finds only a note from Carmodi, who has tracked down Rhian’s father and then Rhian herself. When Rhian’s younger self arrives in the cell, Rhian tells her what is to come and then sends her back out to get Anji and the younger Carmodi out of the ship before the bomb her father has planted goes off. The Doctor also departs, and when the bomb goes off, the ship is taken out of time completely -- causing a paradox which will eventually cause the closed circuit to unravel.