When Miss Pongleton is found murdered on the stairs of Belsize Park station, her fellow-boarders in the Frampton Hotel are not overwhelmed with grief at the death of a tiresome old woman. But they all have their theories about the identity of the murderer, and help to unravel the mystery of who killed the wealthy Pongle. Several of her fellow residents, even Tuppy the terrier, have a part to play in the events that lead to a dramatic arrest. This classic mystery novel is set in and around the Northern Line of the London Underground.