While driving in a stormy night on a lonely road in the countryside, Philip Waverton, his wife Margaret and Roger Penderel seek shelter at a creepy old house. Horace and his sister Rebecca Femm are reluctant but receive the travelers and warn that the butler Morgan is a dangerous man when he drinks. When they have dinner, a man called Sir William Porterhouse arrives in the house with his girlfriend Gladys DuCane seeking shelter. Out of the blue, the light goes out and they split to get candles and lamps, while Roger and Gladys go to the car to get a bottle of whiskey. While they drink and talk together, the drunken Morgan attacks Margaret and Philip along a most unusual and bizarre night.