One Mysterious Night

One Mysterious Night is a 1944 crime film, the seventh in a Columbia Pictures series starring Chester Morris as reformed crook Boston Blackie. It was preceded by The Chance of a Lifetime and followed by Boston Blackie Booked on Suspicion. Blackie is called upon to recover a stolen diamond.

Daleys sister Eileen finds out that her brother is involved with thieves Paul Martens and Matt Healy, and that he later hid the diamond in her purse. She persuades him to give the jewel to Blackie. However, his former partners show up just after he meets Blackie. In the ensuing scuffle, they kill Daley, and kidnap Blackie and his sidekick, the Runt. The crooks figure that, with Blackie missing and unable to clear himself, he will be suspected of both the robbery and the murder. Indeed, Farraday begins to believe just that.Blackie tells his captors that what they have is a fake that he intended to switch with the real diamond, supposedly stored in a vault. Uncertain, they take it to fence Jumbo Madigan to get his expert opinion. Blackie manages to free himself and the Runt, and persuades Madigan to go along with his story. However, when the police surround the place, Martens and Healy realize they have been double crossed, and shoot Madigan, though not fatally. When the cops break in, they do not spot the pair, posing as mannequins. ........

Source: Wikipedia