British crime film directed by Peter Duffell and starring Bernard Lee, Moira Redmond and John Van Eyssen, loosely based on the 1918 novel "The Man Who Knew" by Edgar Wallace.
A slick young man buys a jewel with a cheque that bounces. He then disappears and both the police and a lawyer try to find him. The lawyer hires a female detective to track down the missing man, but when his body is found in the Thames the case is by no means over.
