The Keep is a horror film directed by Michael Mann and based on the novel of the same name by F. Paul Wilson. The film is set during World War II and follows a group of Nazi soldiers who occupy an ancient fortress in Romania.
The soldiers soon discover that the keep is home to a powerful and mysterious entity known as Radu Molasar, who begins to wreak havoc and death upon them. As the body count rises, the Nazis must figure out a way to defeat the entity and escape from the keep before it's too late.
However, when a Jewish historian arrives on the scene, he realizes that the entity was imprisoned in the keep for a reason and that releasing it could have catastrophic consequences for the world.
The Keep features an ensemble cast that includes Scott Glenn, Gabriel Byrne, Jurgen Prochnow, Ian McKellen, and Alberta Watson. It received mixed reviews upon its release in 1983, but has since gained a cult following among horror fans.