The evil Dr. Mabuse develops a death ray with which he threatens the world.

A company's stockholders hold their meeting at a lonely mansion. A mad doctor conducting experiments in the mansion starts to strangle them one at a time with a nylon noose. The survivors must figure out a way to stop him.

A British woman on a visit to post-war Berlin is caught up in an espionage ring smuggling secrets into and out of the Eastern Bloc.