Camilla is still convinced there is a mouse in the house and Renzo humors her. At school, there is some tension, but Marchesi has some information for Camilla and her mood changes. Berardi also obtains, almost by accident, some intriguing information, that could be pertinent to the case.

Camilla can't help herself and goes to the home of Mattioli's former nurse. Gaetano leaves Camilla a text message. Note that in Italy, texting while driving is now prohibited.

Camilla, in conversation with her mother, hopes that the postcard from New York is just a misunderstanding. Renzo has a moment of truth by a dumpster. Later, he says something about Dr. Mattioli that gives Camilla an idea about her "hallucinations."

The mouse is still an issue at Camilla's house. At police headquarters, Berardi has his hands full with the mother of the murdered detective and Mattioli's wife.

After her trip to the Tiber River, Camilla goes to pick up Livietta at Giulio's house, where the two kids are dancing to Merengue. Camilla has some questions about that. Meanwhile, Berardi and Torre are busy with the coroner, identifying a corpse.

Renzo comes home late after a meeting and finds Camilla on the couch deep in thought. She lets him know she has been connecting the dots between the postcard and the merengue instructor. She goes off to bed but finds a surprise on the way.

Having read about Mattioli's death, Camilla rushes to Berardi's office, where he is checking some documents with Torre. She participates and comes across an interesting piece of information.

Berardi and his men go after Marino Monti who is at the martial arts center. It was very upsetting for Camilla to see it all so close up. She has a drink with Gaetano to calm down.

The police question the man they caught fleeing the martial arts center and are able to tie up a lot of loose ends. Gaetano and Sonia discuss the case over dinner, but the inspector's mind is elsewhere. Renzo is finally convinced that Camilla wasn't having hallucinations when she saw the nurse's body upstairs.

Mattioli's wife talks to Berardi and tells him what she knows so that they can find the body of the nurse. At school, Camilla's class discusses the book "L'Esclusa" by Pirandello. The usual translation of the title is "The Outcast," but literally, it is "the excluded woman."

It's time for an official introduction to Camilla's mother's fiance. Everyone is a bit tense. Camilla then gets a phone call that changes the course of the evening.

Camilla and Renzo go down to the morgue to identify the dead body. They take with them the earring Renzo found in the stairwell near Mattioli's office. Back home in bed, they discuss some peculiarities regarding the earrings and the corpse.

Both Camilla and Gaetano, for different reasons, arrived at a similar conclusion about the earring. Piccolo and Ferrari have a job to do, but they also do some personal talking.

Mattioli's widow recounts the story, told through her eyes, of the murder, including what she heard in the stairwell of the building.

The case has been solved and it's the last day of school for Camilla and her students. Who will flunk and who will be promoted?