The Doctor is about to take Emily and Will back to UNIT HQ when he receives a distress signal. The TARDIS materialises in a crater, which Will realises is the result of a bombing. They have arrived in London during World War II.
The Doctor tracks the signal and they head to the White Rabbit. In the pub are three people: Len, the bartender, a woman named Eleanor and a man reading a newspaper. The Doctor and his friends sit at a table and drink. When Emily stands up to remove her coat, another man comes into the pub and trips over her, spilling her drink. The Doctor recognises the man, who calls himself Albert Weston.
The group heads for the cellar when an air raid begins. Len, the Doctor and Albert talk, and they depress Will enough that he brings out a harmonica and plays a song. Emily is furious at him because she thinks the song is from the 1970s and Will has changed the past, though the Doctor assures her that it's difficult to change time and the song is probably older than the 70s anyway.
Eleanor, meanwhile, has been watching the others scornfully and is angered to find Albert watching her.
The Doctor and his friends, who have been watching Albert, notice that he has obviously had military training. They think he is the source of the distress signal. The Doctor confronts him, calling him Edward Grainger, and Edward pulls a gun on them.
Emily and Will try to disarm Edward, resulting in Emily being shot. Will captures Edward and handcuffs him, while the Doctor and Eleanor work on Emily. After accusations on both sides, Edward and the Doctor realise that each has thought the other sent the signal. The Doctor looks suspiciously at Len, but Len tells him the man with the newspaper has left the cellar.
Edward and the Doctor give chase, and when they reach the man, the Doctor tells him that he can take him home. The man, a Mim, has been trapped on Earth. He's the one who sent the signal.
The Doctor and his friends take the Mim to the TARDIS and take him home to the Mimsphere. Meanwhile, Edward, back at the pub, offers to walk with Eleanor, though she snubs him.
Once the Mim has been dropped off, the Doctor takes his friends back to their time. He accuses Emily of wearing alien technology that prevented the bullet from killing her, and she sarcastically apologises. Before they head off to the pub together, Emily first wants to check UNIT records to see if the past has been changed. A search of UNIT archives reveals that the records are missing, so the Doctor proposes a trip to the 1950s to find them.
- The Doctor and Will discuss The Muppet Show, Gonzo and Rowlf.
- Eleanor is drinking sherry.
- Eleanor works at Bletchley Park.
- The stories in Short Trips: The Centenarian revolve around Edward Grainger, a man who has met the Doctor more than a dozen times over the course of his life.
- This story is the second in a trilogy of stories featuring the Sixth Doctor, Chaudhry and Hoffman. It comes between The Terror of the Darkness, in Short Trips: A Day in the Life, and Defining Patterns, in Short Trips: Defining Patterns.