This crime story is set in the city of Matera in the Basilicata region, where Immacolata (Imma) Tataranni is the deputy prosecutor. She's on vacation at the beach when she finds something odd in the water.

As Lara and Luca go to question the victim's wife, it turns out a third dog has gone missing. Luca can't help but notice how self-assured Lara has become.

With some prodding by Marta, the scene where Luca is lying on the ground and says "I love you" comes into focus for him.

Marta and Luca manage to figure out what happened, and Luca tells the story to his boss, Casadio. Manara gets out of the office with the excuse of a physical therapy session.

Marta and Luca are getting closer to the truth and gradually find more pieces to the puzzle, thanks, in part, to some good police work by Barbagallo and Buttafuoco.

Rivera and Manara review the surveillance video of the bus and see something new. Meanwhile, Tiziana seems to have fallen in love.

After questioning the bus driver, Luca isn't convinced he's the murderer. Meanwhile, Tiziana doesn't seem to be taking house arrest very seriously.

Marta is very convincing in her role as a sexy dancer at the night club, maybe too convincing. The situation takes a darker turn and she gets more and more concerned.

Luca is very upset with his sister. He feels betrayed and starts getting really worried, both for her and for himself, since he has gone out on a limb for her. The investigation continues.

Luca goes to see Ginevra about the autopsy, but he confides in her, too. Toscani is having trouble telling Luca the results of his investigation into the passengers of the bus.

The contents of the blue backpack point to a possible motive. Luca talks to his sister again, but she is still visibly upset, which is understandable. Marta finally talks to Luca about what has been weighing on her for a while.

During questioning, the passengers seem to agree about one person getting back on the bus during the rest stop: Luca's sister. Buttafuoco and Barbagallo finish up checking the luggage, but they come across an extra bag.

Manara is back in the saddle. Raimondi leaves for Rome after a frank conversation with Luca, and another one with Marta. Quattroni has some important information weighing on him, and goes to talk to Manara.

Manara, and Raimondi meet with their chief, Casadio to discuss the case and Manara's status, but the meeting has an unexpected outcome. Meanwhile, the only real suspect is Luca's sister!

Tiziana is confused because she has no clue that she might be a suspect. Raimondi, who shows up with Rivera, is confused because he doesn't realize Tiziana is Luca's sister. Poor Tiziana!