The first and possibly the greatest pairing of Lugosi and Karloff is one of the darkest, most macabre horrors ever made. Dr Werdegast (Bela Lugosi), a POW for fifteen years has been freed and now seeks news of his wife and daughter and vengeance on Hjalmar Poelzig, the man whose betrayal lead to his imprisonment and the deaths of thousands of his countrymen during the war. He tracks him down to the castle he has built on the site of their old fortress and soon discovers the diabolical secrets held within its walls. Poelzig is now the leader of a satanic cult, engaging in macabre practises and rituals. One man's pure evil against the others tormented need for revenge leads to an absorbing battle and a shocking climax.