Once Adam has recovered, the Doctor leads him and Rose back to the arcade, telling them that this era represents human culture at its finest. But as he speaks, the kiosk in the centre of the arcade opens up to reveal a fast-food booth, and men and women pour into what is now revealed to be a canteen to buy kronkburgers and other greasy, quick-fix foods. There’s no sign of the high culture or multitude of alien life forms that the Doctor was expecting. Puzzled, the Doctor fiddles a cashpoint machine with his sonic screwdriver to provide Adam and Rose with a credit bar, and sends them off to experience the culture for themselves while he investigates. He does so by stopping two passing women, Suki MacRae Cantrell and Cathica Santini Khadeni, and asking them where he is and what happens there. They are bewildered at first, but then it occurs to Suki that this must be a management training exercise, which the Doctor “confirms” with his psychic paper. Cathica, who’s eager for a promotion to Floor 500, explains that this is Floor 139 of Satellite 5, where the news is packaged and broadcast to the human empire on 600 channels (including Bad Wolf TV, on which the Face of Boe has just announced his pregnancy).

Elsewhere on the station, the Editor has sensed something amiss. He is a pale man who works in a room with frost on the walls and floor; the men and women stationed at the room’s computer terminals are stiff and unresponsive, as if frozen solid. The Editor orders them to track down the disturbance he’s detected, and they soon narrow it down to the Doctor, Suki and Cathica. The Editor orders his minions to keep a close eye on these three and to triple-check their background and security clearances.

Rose picks up a drink called zaffic, which is like a beef-flavoured Slush Puppie, but Adam is too overwhelmed to try eating or drinking anything. Rose sympathetically loans Adam her cellphone, which the Doctor modified to help her overcome her first experience of culture shock. Adam is astonished to find that he can leave a message on his parents’ answering machine, over 198,000 years in the past. The Doctor then calls Rose and Adam over to see Suki and Cathica at work -- and Rose fails to notice the thoughtful expression on Adam’s face as he pockets her cellphone.

The Doctor and his companions accompany Suki and Cathica to a media suite, where Suki joins a group of men and women around a circular dais of computer terminals with hand-pads, while Cathica lies on a couch beneath a glowing sphere set into the ceiling. Trying to impress the Doctor, whom she still believes to be management, Cathica makes a point of reminding her fellow journalists that they must gather the news honestly and without bias; she is irritated when Suki points out that this is not just company policy, but the law. Once everyone is in position, Cathica snaps her fingers, a circular port opens in her forehead, and a spike of energy surges out of the sphere into her brain. The other journalists press their hands against the panels, concentrating deeply. The Doctor explains to Adam and Rose that the journalists all have chips implanted in their heads; Suki and the others are collecting information, and Cathica’s brain is processing, collating and packaging the news before transmitting it to the Empire. If knowledge is power, then these could be the most powerful people in the entire Empire. But while Adam is impressed with the technology, the Doctor knows that there’s something wrong with it...

The Editor has finally traced the security breach -- to Suki, who is not what she seems. The Editor orders his workers to intercept her scan, and soon determines that her official biography has been tampered with. An alien voice roars its displeasure at the Editor, who apologises desperately for their failure to detect her earlier and orders his minions to summon her to Floor 500 immediately. Down on Floor 139, Suki has been cut out of the network, interrupting Cathica’s information flow -- and to Cathica’s shock, they are then informed that Suki has been promoted to Floor 500, even though she’s relatively new here and Cathica has been applying for a promotion for three years.

Later, as Suki prepares to leave Floor 139 behind, Rose chats with Adam, who seems a bit overwhelmed by everything. Claiming that he needs to be alone for a while to let this all sink in, Adam tells her that he’s going to go sit on the observation deck for a while; she offers to come with him, but he tells her that he knows she’d really rather be with the Doctor. Rose gives him the TARDIS key in case he needs to get away from it all, and Adam leaves, a private little smile crossing his face. Meanwhile, the lift arrives to take Suki to Floor 500, and she bids Cathica a tearful goodbye before departing. Cathica, still bitter, is glad to see the back of her -- and the Doctor is surprised when Cathica reveals that they’ll never see Suki again. Only those who are promoted get an access key to Floor 500, and nobody who’s gone up there has ever returned...

The lift arrives at Floor 500, which is superficially similar to Floor 139 -- except that unlike the overheated lower levels, it’s actually snowing, and frost has formed on the walls and floor. Suki cautiously explores her surroundings, and finds a media suite like the one on Floor 139 -- with shrivelled, skeletal corpses in the seats. A door opens up to reveal the Editor’s suite, and when Suki enters, the Editor reveals that he knows her true identity. She is not really Suki MacRae Cantrell, born in the year 199’89 in the Independent Republic of Morocco; she is Eva Saint Julienne, a self-proclaimed anarchist and the only surviving member of the Freedom Fifteen. “Suki” pulls a gun on the Editor, revealing that the Freedom Foundation has positive proof that Satellite 5 has been manipulating the facts and distorting the news to control the population of the Empire. But the Editor reveals that he’s not the man in charge; there is someone above him, quite literally. The true boss of Satellite 5 descends on Suki as the terrified woman fires her gun repeatedly at it, to no effect...

On the observation deck, Adam accesses a computer terminal and asks it for a history of the microprocessor from the 21st century to the present day. He then uses Rose’s cellphone to leave a message on his parents’ answering machine, but he barely gets started before his terminal crashes with an error message directing him to Floor 16. Floor 16 turns out to be the non-emergency medical centre, where Adam learns that in order to access the satellite’s computers, he’ll need to get a chip implanted in his head. He is hesitant at first, but gives in to temptation when he realises that the operation will enable him to connect to any terminal on Satellite 5. The nurse assumes him to be a hick student from the University of Mars, but when she discovers that he has unlimited credit through the bar the Doctor gave him, she upsells him on an infospike, like Cathica’s head portal. The ordinary headchip costs 100 credits and enables him to interface with the station’s terminals, but the full infospike effectively turns his brain itself into a computer terminal, allowing him to download and transmit any information about the history of mankind from Satellite 5’s archives. According to the nurse, the surgery is quick and painless -- and Adam is unable to resist temptation.

Cathica’s media centre has been shut down for maintenance, and the Doctor takes the opportunity to question her further about Satellite 5 and its operations. She finally realises that he’s not from management at all, and, worried, she tells him to leave her out of whatever he’s doing; however, she doesn’t actually ask him what that is, which the Doctor points out is the exact opposite of the way a journalist should behave. He questions her about the absence of aliens on Satellite 5, and learns that the price of spacewarp has increased, immigration laws have been tightened up due to unspecified threats, and the government on Chavic Five has collapsed -- a number of little, plausible reasons that Cathica has never questioned, but which add up to mean that there are no aliens at the hub of Empire. Cathica doesn’t believe that this is a conspiracy, but the Doctor claims that the headchip and infospike technology he’s seen is about 90 years behind the times -- which means that something started to hold back humanity’s progress, and it happened just after Satellite 5 began broadcasting.

The Doctor leads Rose back out into the canteen, where he finds a quiet corner and pulls open a wall panel, accessing the computer mainframe. Cathica protests, but doesn’t actually do anything to stop them, which is no more than the Doctor has come to expect; by now, he’s clearly given up on her. When Rose comments on the stifling heat, Cathica claims that she and the others have complained about it to no avail -- and again, the Doctor points out that nobody has ever bothered to investigate for themselves. Once he gets into the computer, he calls up a schematic of the satellite’s plumbing -- and Cathica is surprised to see that the air conditioning systems are working at full power, and are channelling massive amounts of heat away from Floor 500, down into the rest of the satellite.

By now, the Doctor’s meddling has been noticed on Floor 500 -- much to the Editor’s surprise, as the computer had spotted nothing amiss about the Doctor while monitoring his conversation with Suki and Cathica. The thundering alien voice orders the Editor to investigate, and he sets his minions to work -- including Suki, who is now sitting before a terminal, as frozen and dead-eyed as all the others. The computer finally reports that the Doctor and Rose apparently don’t exist; there is no record of them anywhere in the Empire. Fascinated, the Editor orders his minions to summon them to Floor 500.

Down on Floor 139, the Doctor tries to get an access code for Floor 500 out of the computer, and succeeds more quickly than he’d expected. He and Rose board the lift, but Cathica has had enough and stays behind; however, while she just wants to avoid trouble, she’s clearly a little upset by the Doctor’s lack of interest in what happens to her. The Doctor and Rose also assume that Adam has had enough, but they’re both happy not to have a third wheel along. The lift delivers them to Floor 500, where they find their way to the Editor’s suite; there, Rose sees Suki and tries to draw her attention, but to no avail. The Doctor realises that the workers here are dead, their headchips keeping their bodies just animated enough to do the Editors’ bidding. The Editor demands to know who the Doctor and Rose are and how they’ve managed to keep themselves hidden from the Empire, and when the Doctor refuses to tell them, the Editor’s frozen minions grab him and Rose, holding them in place while the Editor introduces them to his superior. Hanging from the ceiling is a monstrous, slug-like creature with a single, snapping mouth full of razor-sharp teeth; this is the Mighty Jagrafess of the Holy Hadrojassic Maxarodenfoe (“Max”, for short) -- and it is the true ruler of the Fourth Great and Bountiful “Human” Empire.

Adam has had a port installed in his forehead; it’s set on default mode, which means it opens with a snap of the fingers. Overwhelmed, he tries to throw up, and learns that he’s also had a vomit-o-matic installed as a special bonus offer; when he vomits, nanotermites in his throat lining freeze the waste into a neat and tidy frozen chunk. Now prepared to access the station computers, Adam returns to Floor 139, where Cathica, despite herself, has been thinking about what the Doctor told and showed her. Unable to let it go, she returns to the wall panel, gets the access code to Floor 500, and takes the lift up to see the truth for herself. This means that the media centre is unoccupied when Adam returns, and he takes his place on the central couch, calls home on Rose’s cellphone, and uses his infospike to beam information directly out of the Satellite 5 archives and onto his parents’ answering machine.

Up on Floor 500, the Doctor and Rose have been fitted with electronic manacles, and the Editor is explaining that the “news” from Satellite 5 has been carefully engineered to create a climate of fear within the Empire and manipulate the population without their ever being aware of it. The Editor works for a consortium of banks who are happy to let the Jagrafess secretly rule the Empire as long as it ensures long-term stability for their investments. Whenever somebody notices that something is wrong, the Editor senses it through their headchips, and brings them up to Floor 500 to dispose of them. As the Editor speaks, the Doctor notices Cathica lurking in the doorway, listening to everything he’s saying. The Doctor thus turns the topic to the air conditioning system, which he now realises is in fact a life support system for the Jagrafess; it has a life expectancy of 3,000 years, but a very fast metabolism that produces a great deal of heat, which is pumped out of its body and down into the lower floors.

The Editor begins to torture the Doctor and Rose, sending bolts of energy through their manacles and demanding to know who they are, where they’re from and what they’re doing. Suddenly, however, he knows everything he needs to know about the Doctor, apparently without needing to be told. The Doctor is stunned and furious when the Editor reveals that Adam has connected himself to Satellite 5’s archives -- and in the Floor 139 media centre, Adam is convulsing as information starts flowing out of his brain instead of into it. The Editor now knows the Doctor to be the last of the Time Lords -- and through Adam, he now has the key to the TARDIS. With access to time-travel technology, the Jagrafess will have the ability to rewrite history and prevent the human race from ever having developed in the first place.

Cathica realises that everything the Doctor told her was true; like the rest of humanity, she’s been bred to be a docile, stupid slave who doesn’t bother asking questions about the world around her. She heads straight to the Floor 500 media centre, pushes the corpses out of the way, sits on the central couch and activates her infospike. Before the Editor realises what’s happening, Cathica cuts Adam out of the network and sets the air conditioning system into reverse, pumping heat into Floor 500 instead of out. The entire station starts to quake; down on Floor 139, the dazed Adam stumbles out of the media centre to find himself in the midst of a panic-stricken stampede as the station shudders around its employees. The Editor is completely unprepared to deal with an employee capable of thinking for herself; he orders his minions to burn out their minds, but Cathica cuts them out of the network, and their bodies drop to the floor, no longer animated. Rose’s manacles snap open, and she uses the sonic screwdriver to free the Doctor as well. The Doctor and Rose flee as the Jagrafess’ body begins to overheat and swell up, and the Editor quickly tenders his resignation and tries to flee. However, Suki’s body suddenly reaches out and grabs him by the ankle, tripping him up and pinning him in the room as the Jagrafess swells up and explodes.

With the death of the Jagrafess, the human race is free to progress without their knowledge and ambitions being curtailed. As Cathica prepares to deal with the aftermath, the Doctor prepares to deal with Adam. Adam desperately tries to defend his actions, but the Doctor forces him into the TARDIS and takes him straight back home. There, he gives Adam one chance to admit the truth, and when Adam claims to have no idea what he’s talking about, the Doctor destroys his parents’ answering machine with the sonic screwdriver, destroying the tape with the data from Satellite 5’s archive. Adam could have changed all of history for his own selfish gain, and the Doctor thus refuses to let him back into the TARDIS. What’s more, he’s going to leave the port in Adam’s head, even though it will open every time someone snaps their fingers in his vicinity; if Adam wants to avoid having his head cut open by curious scientists, he’ll have to lay low from now on, and he’ll never be able to do anything important with his life. Adam begs Rose to speak up for him, but Rose returns to the TARDIS without a word and departs with the Doctor. Adam’s mum arrives to find her disconsolate son standing in the living room, and is delighted to see him back after six months’ absence. To her, it seems the time has gone by like a snap of the fingers. Unfortunately, she demonstrates...