One night, Bobby Zierath hears strange noises in his closet. He opens it to discover that the TARDIS has materialised inside. He joins the Doctor, Steven and Vicki for a series of adventures. They visit a planet with giant talking mushrooms (called "mooshroos" by Vicki) and ancient Rome, fight robots that looked like drills, rescue Vicki from the "Most High" and meet Conidrons and the Zaksi. Bobby is returned to his home moments after he left (by repeatedly pressing the fast return switch) and leaves the TARDIS with HiFi, given to him by Steven.
He tells stories of his adventures at school and is mocked by his peers. His teacher, Colleen Griebel, grows worried about these stories. Brent Uden from child protective services meets with Bobby's father Victor Zierath and Colleen. He decides Bobby should be separated from his widowed father and placed in a foster home. Bobby endures years of meetings with child psychotherapists until he decides to pretend he had made it all up for attention.
The Doctor and his companions are in the TARDIS. The Doctor detects a disturbance in time, and they need to investigate. They have landed in Indiana in the early 21st century. They do some sightseeing and then relax at a coffee shop. They are accosted by Bobby, who is now ten years older. He accuses the Doctor and his companions of ruining his life. The Doctor has no idea who Bobby is, but is disconcerted by Bobby's mention of Susan.
After Bobby leaves them, the Doctor realises that they must go back ten years and bring Bobby aboard the TARDIS for the adventures he said he had. Steven disagrees, refusing to ruin Bobby's life. Vicki explains that they must in order to avoid a paradox. They visit young Bobby, taking him on his adventures in one night. They return him home, and Steven gives him HiFi as a gift.
Because Bobby knows much of his own future, the Doctor has to remove him from his time and place him in the Time Vortex, along with several others who have been removed from their times.
- As a child, Bobby is a fan of Pokémon.
- Vicki has been researching the history of "Ancient America" in the TARDIS library. She studied temporal paradoxes at school.
- On their journeys in the TARDIS, the Doctor, Vicki, Steven and Bobby encounter robots which resemble drills called the Conidrons, the Zaksi and a being known as the Most High who kidnaps Vicki after she described him as "a cuddly-wuddly."
- Each story in Short Trips: Repercussions includes a character or characters being taken out of their time by the Doctor to avoid harm to the Web of Time. In this story, it is Robert Zierath.
- The Doctor refers to his granddaughter Susan Foreman's departure. (TV: The Dalek Invasion of Earth)
- Following his encounter with his fellow renegade Time Lord the Monk in Northumbria in 1066, the Doctor has installed a device in the TARDIS which is designed to detect further attempts to alter history. (TV: The Time Meddler)
- When Bobby is returned to his own time, Steven gives him his toy panda HiFi as a going away present. (TV: The Chase, The Time Meddler)