The crime.

Frustrated writer-student Siavash stabs his sister's suitor, a wealthy antique dealer/money lender, to death. But cleaning woman Mahtaj witnesses the murder. Something about her rigid, unemotional stare prevents him from killing the only witness to his crime. Instead, he runs first to a friend's house and then home, unable to calm his increasingly erratic behavior. He then suspected her for blackmailing him and goes after her.