Theorem

A wealthy Italian household is turned upside down when a handsome stranger arrives, seduces every family member and then disappears. Each has an epiphany of sorts, but none can figure out who the seductive visitor was or why he came.

• 
  Pier Paolo Pasolini
• 
  Sergio Citti
• 
  Vanda Tuzzi

• 
  Terence Stamp
  The Visitor
• 
  Silvana Mangano
  Lucia, the Mother
• 
  Massimo Girotti
  Paolo, the Father
• 
  Anne Wiazemsky
  Odetta, the Daughter
• 
  Andrés José Cruz Soublette
  Pietro, the Son
• 
  Laura Betti
  Emilia, the Servant
• 
  Ninetto Davoli
  Angelino, the Messenger
• 
  Carlo De Mejo
  Lucia's first lover
• 
  Adele Cambria
  Emilia, the Second Servant
• 
  Luigi Barbini
  Boy at the station
• 
  Giovanni Ivan Scratuglia
  Lucia's second lover
• 
  Alfonso Gatto
  Doctor
• 
  Cesare Garboli
  Interviewer (uncredited)
• 
  Susanna Pasolini
  Old Peasant (uncredited)