The Devil, in the guise of a human, meets a young couple who remark upon looking at a Renaissance painting of a martyr that Evil could never triumph over Good.
Mabel has just gotten engaged during a housewarming party of which her mother is the hostess. When an annoying party guest persuades Mabel to dance with him, Mabel hurries through the dance and then goes to look for her fiancé, only to discover him caressing another woman.
Movie mogul Thomas H. Ince may well have been the director of The Despoiler as indicated by the credits; but since Ince was known far and wide as a glory-hogger, it's also possible that one of his talented lieutenants wielded the megaphone.