Torture Ship (1939)

Starring Lyle Talbot, Irving Pichel, Jacqueline Wells, Sheila Bromley, Anthony Averill
Directed by Victor Halperin
(actor & director credits courtesy IMDB.com)

A scientist trying to correct criminal tendencies in human beings lures a group of hardened criminals aboard a yacht as test subjects, before telling them they may not survive his experiments.

An interesting low budget suspenser from Halperin (director of White Zombie), with an enjoyable cast, the picture definitely entertained me, and I thought Halperin balanced the action, performances, and thrills admirably.  There's lots of familiar faces among the actors, with Pichel playing the unscrupulous doctor, Talbot his straight-arrow nephew captaining the ship, Wells (from The Black Cat) playing a convicted woman who may be an innocent victim or may not, Wheeler Oakman as the chief criminal, and the always creepy Skelton Knaggs as another felon.  The script, which IMDB credits to Harvey Huntley & George Wallace Sayre, based on a Jack London story, is at times overly simplistic, but also delivers its share of surprises and balances roles for the large cast very well.