Truffle hunting is a peculiar activity, one that requires the collaboration of a dog. And you never want to let on how many truffles you find, even if you are friends with other truffle hunters.

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.

Melania talks about her relationship with her father when he was still alive. He didn't say much, but unbeknownst to her, tried to get a story of hers published. She talks about one her favorite parts of Rome: Isola Tiberina (Tiber Island), the only river island in the part of the Tiber that runs through Rome.

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.

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.

This episode is about a specialty from Colonnata, a little village above Carrara, where marble is quarried. It's pork lard, which may not sound very appetizing but is beloved by Italians all over the peninsula. A little goes a long way, but savored with typical unsalted Tuscan bread, it is pretty special. And marble plays an important part.

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."

Melania Gaia Mazzucco talks about one of her novels set in seventeenth-century Trastevere, quite a different place than what we see today. Although she has traveled the world, Mazzucco comes from generations of romani di Roma (Romans from Rome).

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.

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.