The Man Who Knew Too Much

While vacationing in Switzerland, Britons Bob and Jill Lawrence befriend jovial Frenchman Louis Bernard. Not long afterward, Bernard is murdered. He whispers a secret in Bob's ear before expiring. This is witnessed by several sinister foreign agents, who kidnap Bob's daughter Betty to keep him from revealing what he knows: That a diplomat will be assassinated during a concert at London's Albert Hall. (official distributor synopsis)