dr. ben mckenna ( james stewart ) and jo mckenna ( doris day ) travel to morocco for a holiday where they meet a mysterious man name louis bernard ( daniel gélin ) on a bus . the next day this man be murder and but before he die he tell ben a secret while an assassination will take place in london . the crook kidnap the couple son hank ( christopher olsen ) make sure ben would not reveal their plan to anybody . alfred hitchcock the man who know too much ( 1956 ) be a very intense thriller . the acting be superb a it always be in hitchcok film . james stewart be marvelous . doris day be a delightful person and actress and she get to show her sing talent as well . the song que serum and serum have an important part in the movie . this movie be a movie of many classic scene . in the final scene at the albert hall and do without dialogue and you can barely blink your eye . this movie be fifty year old now . time hasn not decrease it power in any way .