Fingerprint evidence puts safe-breaker Sash Moran at a break-in at a diamond merchant in Amsterdam, but Duval finds he has a watertight alibi - finishing a prison sentence in London. He insists he is being framed, and on release travels to Amsterdam - where Duval himself provides the alibi for a second crime. Duval is not convinced, and when he finds the trick to Moran's apparent innocence must try to anticipate his next move.