Salvage operators Gregor (Ashley Walters) and Bram (Mark Oliver) operate the Van Baalen intergalactic outfit with the assistance of an android called Tricky ((Jahvel Hall). When their ship locks onto the Tardis and drags it on board, it sends the Tardis’ systems into meltdown. The Doctor has managed to get himself free, but Clara is trapped inside.
Offering the guys the salvage of a lifetime, the Doctor engages the Tardis’s self-destruct mechanism – starting first at 1-hour, then at 30-minutes – to get them to help him find Clara. Tricky senses that the Tardis is suffering, but Gregor and Bram just want to strip the ship for its valuable gear. When Gregor pulls off a circuit from the Tardis’s architectural reconfiguration system, the Tardis’s protection mode triggers the creation of a labyrinth of mazes.
Meanwhile, something is chasing Clara through a massive library into a series of console rooms. The Doctor deduces that the Tardis is trying to protect Clara and manages to pull her to safety, wherein he explains that a rupture in time is causing the Tardis to leak the past.
When the salvage crew are told the self destruct is a ruse, they try to find a way out. Tricky is then impaled by a giant spike and discovers he is Gregor and Bram’s kid brother (he had lost his sight, voice and memory in a salvage accident). With the monsters closing in, the Doctor, Clara and the brothers enter a room containing the Eye of Harmony where the Doctor tells Clara that the creature chasing her is actually her future self. When Gregor tries to save Tricky from falling into the Eye, the brothers are also turned into Time Zombies.
Pausing at a precipice, the Doctor admits to Clara that he has watched her die twice. When she tells him that she knows nothing, the two jump into the heart of the Tardis and land inside the real console room. Discovering a clue to healing the time rift on Clara’s hand, the Doctor rewrites the day by going through the rift and telling himself to avoid disaster by pressing a big friendly button. Time is then healed, which also means Clara has no knowledge of the entire episode – including the fact she read the Doctor’s name in a book in the library…