The Door with Seven Locks
The Door with Seven Locks is a 1940 black-and-white British film, created and released shortly after the British Board of Film Censors lifted its mid-1930s ban on supernatural-themed and horror genre films. It was based on the 1926 novel The Door with Seven Locks by Edgar Wallace. Released in the United States by Monogram Pictures under the title Chamber of Horrors, it was the second Wallace film adaptation to arrive in the United States, the first being The Dark Eyes of London (called The Human Monster in the US), starring Béla Lugosi, which had been released the year before.
A wealthy lord dies and is entombed with a valuable deposit of jewels. Seven keys are required to unlock the tomb and get hold of the treasure. A series of mysterious events causes the keys to be scattered, and when trying to unravel the circumstances, the heiress of the fortune and her companion investigators become entangled in a web of fraud, deceit, torture, and murder.