Faced with mortgage debts, Professor Nathaniel Billings (Boris Karloff) sells his 18th-century tavern to Winnie Layden (Jeff Donnell), who plans to turn it into a hotel. Billings stipulates as a condition of sale that he is able to continue working in a laboratory in the basement. His housekeeper Amelia Jones (Maude Eburne) and hired hand Ebenezer (George McKay (actor)) also continue to work in the inn. Layden is initially unaware of the nature of Billings's experiments in the basement laboratory: he is attempting to use electricity to create a race of superhumans to help the war effort. Layden's ex-husband Bill (Larry Parks) is against the sale, but is too late to stop it, and decides to stay on at the inn for a few days.