December 1882. Attending the opening of the new Natural History Museum, reporter Alec Lonsdale and his colleague Hulda Friederichs are shocked to discover a body in the basement, hacked to death. Suspicion falls on three cannibals, brought from the Congo as museum exhibits, who have disappeared. But Alec discovers that three other men have been similarly murdered, and when he and Hulda discover a letter in the victim's home warning of a catastrophic event planned for Christmas Eve, they find themselves in a race against time. Who are 'The Watchers', and can the duo stop them before they strike again?