A train accident transforms the Diagnostic Medicine ward into a makeshift emergency room. All doctors are called upon to do their utmost to deal with the emergency. Among the injured, a girl reopens an important chapter in Riccardo's past, which he believed to be forever closed.

Lorenzo is once again struggling with her ex, Chiara, when the girl is hospitalized for an overdose. Marco and his wife feel increasingly threatened by the research that Andrea is carrying out on Satonal, the experimental drug that seems to have caused several deaths. Gabriel, on the other hand, has to explain to his community that he plans to stop.