Mark of the Tortoise

After denying a crime syndicate 100,000 pounds on demand, a British millionaire is soon dead. His nephew Don (Gotz George), heir to the fortune, is determined to get his vengeance and begins his own search for the guilty parties. It would seem Don has fortune on his side as the gang boss (Richard Muench) is having problems not only among his men, but also with his woman. (allmovie.com)