Theorem is the most enigmatic of Pier Paolo Pasolini's four novels. The book started as a poem and took shape both as a work of fiction and a film, also called Theorem, released the same year. In short prose chapters interspersed with stark passages of poetry, Pasolini tells a story of transfiguration and trauma.

To the suburban mansion of a prosperous Milanese businessman comes a mysterious and beautiful young man who invites himself to stay. From the beginning he exercises a strange fascination on the inhabitants of the house, and soon everyone, from the busy father to the frustrated mother, from the yearning daughter to the weak-willed son to the housemaid from the country, has fallen in love with him. Then, as mysteriously as he appeared, the infatuating young man departs. How will these people he has touched so deeply do without him? Is there a passage out of the spiritual desert of modern capitalism into a new awakening, both of the senses and of the soul? Only questions remain at the end of a book that is at once a bedroom comedy, a political novel, and a religious parable.