Blackmail

Hitchcock's first sound film — and a watershed moment in British cinema. A young woman stabs a man who tries to assault her, and her boyfriend, a Scotland Yard detective investigating the case, gradually realizes she's the killer. The film exists in both silent and sound versions (shot simultaneously), and both are remarkable, but the sound version contains innovations that changed cinema: a famous breakfast scene where the word "knife" seems to stab through the heroine's guilt-wracked consciousness, a chase through the British Museum that climaxes on the dome of the Reading Room, and an atmosphere of moral ambiguity that would define Hitchcock's entire career. Anny Ondra is superb as the traumatized heroine, and the film's refusal to resolve the moral dilemma cleanly — she killed a man, but he was assaulting her — feels startlingly modern.