Stewart and Day are on holiday in Morocco when they witness a man murdered. Before he dies, the man (a spy) warns them of an assassination plot to occur in England.
Before they can contact the authorities, some of the assassins kidnap the daughter of the couple in hopes of keeping them quiet.
Returning to London, they must act alone in, not only saving the diplomat targeted for assassination, but finding and rescuing their own daughter before its too late.
The Albert Hall sequence lasts 12 minutes without a single word of dialogue and consists of 124 shots.
Bernard Herrmann (composer of the score) can be seen conducting the orchestra during the Albert Hall sequence. Not listed on the credits, his name can be seen on the poster play bill when Day exits the taxi.
The only true remake by Hitchcock. He first made this film in 1934 with Peter Lorre.