The TARDIS is undergoing difficulties and when it flies off with only Amy inside, the Doctor is left stranded in a Colchester park.
As he tries to work out what is happening and reunite with Amy, he decides to go undercover and becomes the lodger of Craig Owens (James Corden). The Time Lord soon has an unwelcome impact on Craig’s life when he makes too good an impression on Craig’s mates and his potential love interest Sophie.
Meanwhile, strange noises in the flat upstairs appear to coincide with the TARDIS’s bizarre glitches, eerie time loops are occurring and people seem to be going upstairs and never returning. Eventually the Doctor discovers that there is a time engine upstairs and people are being unwittingly lured there to try to launch it.
Craig is all ready to evict the Doctor when they realise Sophie is upstairs and rush to save her. As Amy makes contact and reveals there is no upstairs at all, just the time engine, the Doctor and Craig encounter the computer avatar that is luring people there. Craig is willing to sacrifice himself but as he kisses Sophie, the engine explodes, everything is restored to normal and Amy and the Doctor are reunited.
However, in Craig’s kitchen, a tell-tale crack is glowing…