On Christmas Day 2012, Peter Davison watches the Doctor Who episode "The Snowmen" with his sons. They wonder whether Davison will be invited to return for the upcoming 50th anniversary celebration, or if the special will be reserved for the two most recent Doctors, David Tennant and Matt Smith. Davison dreams of a warm invitation and special treatment, but he is haunted by a nightmare in which Janet Fielding warns that the production team doesn’t want any of the old Doctors back. Davison, Colin Baker and Sylvester McCoy grow increasingly desperate as they await invitations to appear in the milestone episode. They attempt to reach out to executive producer Steven Moffat, only to have their calls ignored and their voicemails deleted.
Davison confides in Baker and McCoy that he has a contact who could help with the plan to join the special. They toy with the idea of bringing in Tom Baker, but his voicemail reveals he’s once again stuck in the Time Vortex. Paul McGann also expresses interest. McCoy departs for New Zealand to continue filming on The Hobbit: An Unexpected Journey, yet boredom drives him to cut his trip short and return to England to join the others.
Davison’s scheme hinges on the three of them (with McGann unavailable due to work commitments) picketing outside the BBC Television Centre. A passing John Barrowman abandons his secret wife and children to chauffeur the trio to Cardiff, where Doctor Who’s production is centered. Back in New Zealand, McCoy’s absence disrupts a scene, though Ian McKellen tells director Peter Jackson that the disruption might be “a slight improvement.”
The former Doctors sneak into the Doctor Who Experience, seize their old costumes, and with the help of Tennant, they infiltrate Roath Lock Studios to observe filming for the special, "The Day of the Doctor." They swap places with three Dalek operators after locking the real operators in their room. After narrowly avoiding security guards, the trio hides on set and then escapes, catching a bus back to London. Davison even deletes a voicemail from former Doctor Who executive producer Russell T Davies asking for a part in his plan.
In post-production, Steven Moffat erases the scene featuring the three Daleks. Yet when the editor reviews footage from the Under Gallery sequence, he notices the former Doctors evading guards by staying under shrouds during filming. The editor chooses to conceal this from Moffat, ensuring that the former Doctors ultimately appear in the special.