Nina is a newly-minted nurse out of training. A derailed train brings a tsunami of patients to the hospital. It falls to Nina to care for Laurent, the driver of the train, devastated by the disaster he caused.
Following an amputation, a young soldier combats fevers and a strange pain. Meanwhile, Nina discovers a secret that one of Costa's patients has been keeping; and a close friend suffers from alcoholism.
A secret between two brothers, at odds since the long-ago death of their mother, comes to light while they are hospitalized for typhoid treatment. Meanwhile, there's something about Pauline.
After undergoing surgery, Nina returns to work despite the protestations of her doctors. The atmosphere in the hospital is tense, and everyone is feeling the pressure.
Nina and Costa cool toward each other, as a new executive arrives to replace Nadine. Fortunately, Nina is distracted from the internal strife when she needs to help a patient receive a bone marrow transplant.
Despite facing the reality of Nadine's death, life at the hospital must go on. Nina, Costa, Leo, Dorothee and Proust all find themselves navigating relationships between fathers and their children.
Nina comes under scrutiny from the family of a young patient she wasn't able to save, while the hospital mobilizes to treat a family with mysterious symptoms before their disease can spread.
While the entire team awaits news of the fate of Internal Medicine, Nina is forced to care for Flora (her daughter's friend) after a night of excess. When Flora's symptoms change, Nina must face difficult facts about her daughter (Lily).