Luca has resolved the case, and Marta arrives with Fabrizio to take over from him. But who could have predicted what happened next?

Marta confides in Ginevra about Luca's declaration of love. Meanwhile, a bus arrives in town, and, as the passengers are getting off, there's a problem. At the same time, Luca is giving Ada a hard time as she drives him to the bus stop to meet his sister.

The investigation gets going. Luca, officially still off duty, had just come to meet his sister at the bus, but naturally, he can't help getting involved in the case, which causes a bit of confusion on the team. Rosmini comes to examine the victim.

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!

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!

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.

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.

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.

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.

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.

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.

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.

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

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.

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.