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.

Lombardi shows up for an informal meeting to talk about a building project. Meanwhile, Imma is driven to Grottole by Matarazzo who is going a bit too fast.

Ottavia and Palma talk about his new apartment and the fact that it is still empty. Lojacono gets some good news from his friend Paolo and shares it with Marinella. He goes to the train station to wait for Laura and gets an idea about the case.

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."

For once, Valentina comes home in a good mood. Imma tells Pietro about her ex-classmate's murder. Don Mariano has a conversation with Samuele, a kid who seems to be in contact with Valentina, but who evidently has had some problems with the law.

Lojacono is not at all convinced that Varricchio killed his own children, especially after talking to him. Pisanello got some bad news about another retiree having taken his own life. Pisanello had been watching over the wrong home.

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.

Imma goes to join Calogiuri in the area of Matera where homes and churches were built into the rock. There are i sassi (cave houses carved out of the rocks) and the lamioni, barrel-vaulted rooms leading to the cave houses. She is guided by Eustacchio, a kid she thinks should be in school. But he knows quite a bit about the history of the place.

Lojacono follows Varricchio to his hotel to ask a few more questions, in private.

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.