Doctor: Matt Smith (Eleventh Doctor)
Companion: Jenna-Louise Coleman (Clara Oswald)
Ashley Walters - Gregor van Baalen
Mark Oliver - Bram van Baalen
Jahvel Hall - Tricky van Baalen
Sarah Louise Madison - Time Zombie
Ruari Mears - Time Zombie
Paul Kasey - Time Zombie
Directed by Mat King
Written by Stephen Thompson
Produced by Marcus Wilson
Executive producer(s) Steven Moffat
Incidental music composer Murray Gold
Series Series 7
Length 45 minutes
Originally broadcast 27 April 2013
The Doctor, sensing animosity between Clara and the TARDIS, decides to teach Clara how to operate it and disables its shields to enable its "basic mode". However, the TARDIS is caught by the magnetic tractor beam of a space salvage ship, damaging the TARDIS. Clara pleads with the Doctor to fix it, but he claims there is no "big friendly button" that can fix everything. Clara spots a strange egg-like device roll across the floor and tries to grab it but burns her hand. The ship jolts and the two are thrown into darkness.
The Doctor awakes to find himself on the salvage ship, manned by the stern Gregor Van Baalen, his brother Bram, and a human-looking android named Tricky with enhanced sensory devices, whom Gregor treats poorly. The Doctor tries to convince Gregor to help him rescue Clara, allowing them to salvage some parts of the ship. Gregor agrees, but when the three join the Doctor inside, he assures cooperation by locking the doors and setting a self-destruct countdown; he will disable it once Clara is rescued. They begin exploring the TARDIS, with Gregor attempting to assess the value of it, though the Doctor warns removing key parts will make the TARDIS angry. Despite this, Gregor orders Bram to start salvaging the console, during which he is killed by an ossified humanoid creature. After removing part of the architectural reconfiguration system, Gregor, Tricky, and the Doctor become trapped in a loop of corridors; the TARDIS is preventing the theft of its systems.
Clara, meanwhile, wakes up in a TARDIS corridor and tries to find her way to the console room. She is pursued by an ossified creature and hides in various rooms, including the TARDIS library where she reads from The History of the Time War before she's forced to flee. Her hand continues to ache from the burn, but she sees the burn marks resolving into letters. She ends up in the console room, where another ossified creature, mimicking her movements, approaches her.
The Doctor, Gregor, and Tricky reach the console room, and the Doctor senses Clara in an echo of the console room. With the help of Gregor's scanner to identify Clara, the Doctor creates a temporary link and grabs Clara before the creature touches her. Gregor demands the Doctor end the countdown; the Doctor, though revealing the self-destruct was a ruse to get their cooperation, finds the TARDIS engines are damaged due to the leakage of time caused by the incident, and they must go to the engine room by way of the Eye of Harmony to prevent it from exploding. En route, Tricky is injured and in pain, to his surprise; Gregor reveals that Tricky is human and also his brother; after an accident that cost the life of their father, Tricky had lost his memories and had special implants to replace his eyes and voicebox. Gregor acted as if Tricky was an android to claim the captaincy of the salvage vessel. The Doctor comments on Gregor's treatment of Tricky and suggests he can do better.
While traveling through the Eye of Harmony, the four are trapped by ossified creatures. When Gregor scans one and it is identified as Clara, the Doctor confesses these creatures are themselves from the future and tries to prevent that future from happening. However, Gregor and Tricky contact themselves and become the conjoined ossified creature, seen earlier. The Doctor and Clara flee towards the engine room but come across a chasm with no way across. The Doctor, thinking they are going to die, asks Clara to explain who she is and how she could have died twice before. Clara doesn't understand, and the Doctor realises she has no knowledge of their previous encounters and is simply a young woman. The Doctor and Clara then leap across the chasm, believing that it is an illusion the TARDIS is using to scare off others.
Reaching the engine room, they find the engine has exploded but the TARDIS has placed the room in time stasis as a safety measure. Clara looks at her hand, the burn marks formed into words - "big friendly button". The Doctor realises they need to go back to the point of the disaster and activate the magnetic beacon - the device Clara picked up - to stop the magnetic tractor and prevent the disaster. They race to the console room, where the Doctor takes the discarded beacon and prepares to travel through a time rift. Clara asks what she will remember and says she knows the Doctor's name from reading the Time War book; the Doctor promises her that she will remember nothing. The Doctor crosses through himself and gives the beacon to his younger self. The younger Doctor reads the side of the beacon - "big friendly button" - and hits the button on top.
Time resets to before the events of the episode. The TARDIS vanishes from the Van Baalens' scanner, and they continue on, though in this new timeline, Gregor has become more appreciative of Tricky, having recalled the Doctor's words. The picture of Gregor and Bram with their late father (seen at the start of the episode) is now shown to include Tricky. In the TARDIS, the Doctor tells Clara that anything can happen to her since she's run away in a box with a madman; she tells the Doctor that's what she's counting on.