This is a good B-grade action feature that makes good use of an involved story of intrigue. It's an example of how low-budget, shabby looking sets can actually help the atmosphere if they go with the right story, and meanwhile the story itself moves at a decent pace as things gradually unfold.
Barton MacLane and Leif Erickson are the stars and antagonists. MacLane is "Captain Scarface", who is masterminding an evil and destructive scheme, while Erickson is a character designed as a Bogart-type antihero who finds himself in the right place and time to try to stop it. Erickson is solid in his role, while MacLane seems to relish his slightly outlandish character, making him interesting and menacing, if not always fully believable.
All of the action takes place either at a shabby-looking port-side hotel or on the captain's equally rundown-looking freighter. The no-frills look of both sets makes them believable and helps the atmosphere, since putting the characters in such settings implicitly makes them too seem rather small and tattered.
The story itself is easily interesting enough to hold your attention for the running time of slightly more than an hour. The actual plot of the bad guys comes across as somewhat far-fetched, but it is mostly a device to drive the intrigue. The story telling has a few rough edges, as can sometimes be the case with movies of this kind, but it has more than enough pluses to cancel these out. It's definitely worth seeing if you like movies of the genre.