Marianne and Jacques, a young middle-class couple, reside in an elegant Parisian apartment with their two small children. One day, Marianne is surprised by an unannounced visit from two strangers, Mr. and Mrs. Worms, who assert that they spent their childhood in the same apartment and request a brief tour of their old home. Marianne consents, but shortly after the enigmatic Worms depart, events take a baffling and ominous twist…