Destination Murder (1950)

Laura Mansfield's father is killed, apparently by a telegraphic messenger. She spots Jackie Wales in a police lineup but can't identify him positively. Later, she arranges to meet him and is convinced he was the killer, but he was acting for someone else. She gets to know Jackie to find out who the boss is, taking a job in the Vogue Club, owned by a man named Armitage. Meanwhile, Alice, Armitage's greedy mistress, goes after Jackie and lures him into blackmailing the nightclub owner. Armitage discovers the betrayal, and kills the two, but Laura schemes to get closer so she can prove him guilty.