Four drunk men get on the London Underground train around Christmas. One of them, Paul, begins acting strangely, as if he were sick. The Doctor and Jo get on the train, and the Doctor points a device at the various passengers. It detects that Paul is an alien, and the Doctor fights "Paul" while the lights flash on and off. "Paul" disappears.
The Doctor and Jo leave, and the witnesses to the event give their reports to UNIT.
- The third witness mentions DVDs, Die Hard, Xbox and iPods. He thinks the Doctor looks like Prince from Purple Rain. He listens to Pearl Jam and Motörhead.
- Veronica and her family celebrate Hanukkah.
- This story is told as eyewitness accounts to UNIT. The Brigadier signs the reports, with Emily Chaudhry and Will Hoffman as witnesses.
to be added