Tom mistook the Doctor’s time machine, Tardis, for a real police telephone box while attempting to foil a jewel robbery. He accompanied the Doctor, together with his niece Louise and granddaughter Susan, to the year 2150, where they discovered that the Daleks had invaded Earth. After helping to defeat the Daleks, the Doctor returned him to London a few minutes before the robbery was due to take place, enabling him to catch the thieves. The temporal paradox created by this action is not addressed in the film.