Walter Craig, an architect, is summoned down to a house called Pilgrim's Farm by a prospective client whom he does not know. On arrival he experiences strongly the feeling that he has been to the place before. He is taken into the house and introduced by his host to a group of people. These also are familiar, though none of them appear to know him. After somewhat constrained greetings he tells them that he has met them all, and the house, and the situation, is a recurring dream. He explains how this dream always starts quietly and pleasantly - at the present moment - but after a certain small incident invariably begins to darken into ghastly nightmare, culminating in horror - a horror of his own creation - from which he wakes up sweating with fear. He never remembers his dream for more than a few moments after waking, until the next time it occurs. He then describes the incident which will mark the turning point of his dream - the breaking of a pair of glasses belonging to one of the party, a psychiatrist. Increasingly fascinated, the party one by one reveal that each has at some time undergone an "inexplicable" experience. The narration of these make up the body of the film.