As Lidia investigates a mysterious poisoning at a prestigious boarding school, Jacopo digs deeper into their friend's death and Marianna uncovers a lie.

Enrico remains doubtful about running for Parliament while Prosecutor Fourneau and Lidia struggle to connect the victims of a series of brutal murders.

An unexpected wedding is disrupted by an unexpected death. As Lidia looks to get to the bottom of it, Enrico prepares a very important speech.