The sci-fi series dips its toe into Agatha Christie waters when the Doctor (Peter Davison) arrives in 1920s England and becomes embroiled in a murder mystery. When the TARDIS arrives at Cranleigh Halt railway station on a summer afternoon in 1925, the Doctor and his pals are surprised to be met by a chauffeur (Timothy Block) and whisked off to a cricket match. Lord Cranleigh (Michael Cochrane) has assumed that the Doctor has come from Guy's Hospital for the charity event to be held later that night in aid of a sick kids' hospital. There then follows a masked ball, a case of mistaken identity and mysterious, murderous goings on in this two-part homage to the golden age of English whodunnits.