East Of Sumatra was one of those potboiler stories that Universal cast Jeff Chandler in while he was under contract there. The story is a romantic pentagon set in the exotic location of an Indonesian jungle with all the men acting with exceedingly high testosterone levels.
John Sutton who is engaged to Marilyn Maxwell without knowing she was once Chandler's girl becomes Chandler's boss on a new job set for one of the thousands of islands in the Indonesian archipelago where the rule of Achmed Sukarno hasn't gotten hold yet. The island is ruled by King Anthony Quinn who has a special girl in Suzan Ball. But Ball is checking out Chandler and the rest of his crew as they start a tin mining operation.
No need to go into all the details, but it all blows up quite nicely with the natives making war against Chandler and his crew with Sutton stupidly bringing Maxwell along into harm's and Jeff's way. It ends in tragedy for one of the five principal cast members.
The film is based on a Louis L'Amour story which since he wrote westerns may have begun as that and Budd Boetticher directed East of Sumatra. Both these guys should have stuck to the American west.