A beautiful, charming nightclub singer, Connie Larrimore, becomes caught up in a sinister plot to steal a $3 million fortune when she appears at The Golden Eagle Club. The nightclub is owned by Gregory Benez, an unscrupulous man who has hired Connie to sing. Government Postal Inspector Bill Davis has a watchful eye on the corrupt Benez and becomes suspicious of Connie's connection to him. When a mail shipment of millions in cash is stolen by Benez and his gang during an unexpected flood, the inspector suspects Connie had a hand in it. The singer must confront Benez to prove her innocence, but the scheming criminal has no intentions of letting himself be caught.
Postal Inspector was Bela Lugosi's last film on his original Universal contract that began with his role in Dracula. Ironically, the actor was displaced from Universal's Dracula sequel (Dracula's Daughter) the same year, but given the role of Benez in this film, an unusual musical drama. Although Lugosi plays the corrupt nightclub owner with the look of the vampire Count, it's really a rare opportunity to see the actor in a dramatic role outside the confines of the horror genre. Actor Ricardo Cortez also appeared with Lugosi's partner in horror, Boris Karloff, in The Walking Dead (1936). Hattie McDaniel (Mammy in Gone With The Wind) rolls her eyes in a supporting role. Universal used real stock footage of a devastating flood that took place in the Northeast U.S. for the scenes of destruction that punctuate the fast-paced film's second half.