London, 1929. Bank clerk Selby Bigge longs to escape monotonous work and a dreary bedsit for a more exciting life. A friendship with Patrick Duker, son of a wealthy banker, introduces him to expensive dinners and parties at a Hampstead Heath mansion. Behind the glamour, the family is divided by scandal, harassment and fears over inheritance. When someone is found strangled after a party, Selby realises that every guest has a possible motive, including himself. To identify the killer he must investigate this dangerous social circle while concealing his own sexuality, which could expose him to criminal prosecution.