The Fifth Doctor tries to teach Turlough cricket. In the process (and with Turlough being bored out of his skull), they accidentally end up investigating strange happenings in London in the year 1702.
A mysterious card player named Nikolas Valentine has been linked to disappearances over the years. Turlough immediately manages to wander off and get into trouble, and finds himself caught up in the case a lot more intimately than he'd have liked. With some reluctance at having to play the hero, he saves the life and virtue of a kitchen maid named Hannah.
The Doctor, meanwhile, befriends a man named Dr. Samuel Holywell, and takes an interest in his new friend's affinity with ghosts and seances. He theorises that Samuel may have some latent psychic ability that allows him to see these "ghosts", and they decide to hold a seance. When that fails to lead to any conclusions, the Doctor drags Hannah along to simply go confront Valentine by knocking on his door and saying he's come to read the meter.
Hannah turns out to be an intergalactic hero, who has vowed to avenge the people killed by evil space alien Valentine. When Valentine gives her his But for Me, It Was Tuesday speech, the day is eventually saved when Valentine's now-mutated captives establish a psychic link between their deformed minds.
Tropes:
- Action Girl: Hannah, who is actually an alien hunting down Valentine, and is in human disguise just as he is.
- Chess with Death: Cards with death, actually. Playing cards with Nikolas Valentine is usually fatal. The Doctor is able to figure out what's going on and save himself, with a little help.
- Hoist by His Own Petard: Valentine is killed when the minds of all the people he's kidnapped join together and destroy him, locking onto his bio-data using one of Valentine's own bio-data recording playing cards (earlier wiped by the Doctor).
- Louis Cypher: Valentine makes a little joke about being called "Nick".
