Loan Shark finds George Raft an ex-con come to live with his sister Helen Westcott after his release. Their neighbor and secretary to the owner of the factory where Westcott's husband is employed, Dorothy Hart puts in a good word for Raft for a job.
Owner Charles Meredith has a special job in mind for Raft, investigating and finding out who's behind a group of loan sharks who have been putting many of his employees in their debt. Raft doesn't want this kind of work, but changes his mind when his brother-in-law Bill Phipps is killed.
But unfortunately this involves Raft going undercover and working for the gang until he can find out who the real boss is. He makes a lot of enemies, including Westcott and Hart until the job is done.
The film was done for B picture studio Lippert films and possibly at a major studio it would have had a lot of the plot holes filled. The writing could have used some improvement, but action goes along at a nice pace and Raft is perfectly cast in the hero part. During this time Raft was doing most of his work in B films and some of them are not bad at all. Loan Shark is one of them.