The architect Paolo Scalia continues to receive mysterious postcards: they should have been sent by his sister Emilia, but Emilia has diasappeared. Paolo goes to Venice and with the help of Lisa, a journalist, in an attempt to follow the traces of his sister and to discover what has happened to her. The people they meet all seem to hide something, but it is an enterprising police officer who unravels the mystery of crimes committed in the city and the disappearance of Emilia.
