The fish shop in the heart of Rome, killed a young man, nor his girlfriend, nor the parents have no idea who did it. Lorenzo Fabbri began to study those who would have killed, along with sorting Filippo Gori, which is against Rex. It will be pursued in an attempt to save his daughter Veronica and Logan, where Fabbri tragically lose his life in fiction. Women are threatened by a "mac", which in the scene in question take them hostage. Entry into infiltration, Lawrence and his men were deployed to stop the machine and accomplices in the kidnapping. While the Commissioner's colleagues are involved to stop the gang of mobsters, take Veronica with her and her child, trying to protect them. But before you ask the Commissioner to hide the car is at that point that we understand the challenges of the fourth season. In an attempt to move it, you end up with a bomb equipped with automatically by the "mac". Under the eyes of the faithful Rex, always close to him for the duration of the action, Fabbri explodes in the air. He died as a hero, but always leaving his beloved Katia, his colleague, in pain.