Karloff is Carl Van Molder who lives on an island ruled by Voodoo.
Capt. Pierre Labesch (Rafael Bertrand) is determined to stop the voodoo as the mysterious killing on the island. His young officer Lt. Andrew Wilhelm (Carlos East) tries to tell him that voodoo is very powerful and he should proceed with caution.
The killings continue and even encompass some of Labesch's men until a final confrontation when the cult is attempting a human sacrifice to their voodoo god.
This is probably the least interesting of the final four of Karloff, as it is not put together very well at all. The most entertaining thing about this film in my opinion is the performance by the luscious Yolanda Montes as Kalea.
She is the housekeeper of Van Molder during the day and a hotter than hell voodoo dancer at night. I watch this film for her alone.
I can only recommend this for Karloff completists.