Season 4

Olivia returns to Los Arcos Hospital to start from scratch in a new specialty: General and Digestive Surgery. Blanca faces the admission of her mentor: Silvia, a retired surgeon who now suffers from Alzheimer's. The new surgical residents, Sandra, Gabriel and Almu, face their first day in the hospital under the leadership of Luigi, the chief resident, who acts as viceroy.

Blanca faces her greatest crisis as a surgeon: after the intervention of her mentor, an uncontrollable tremor in her hand caused by stress prevents her from operating. To hide it, she delegates responsibilities to Luigi. The residence is a jungle. The new ones fight to make their place. Sandra begins the trauma rotation where she meets Darío, a bitter patient, who puts her patience to the test.

After a problem at her son's school, Blanca asks Olivia to become his pediatrician to prevent anyone from labeling the child as disabled. Gabriel makes a fatal mistake in an operation. His attempts to cover it up push him to resort to the help of his brother Petru. There will be conditions. Sandra tries to convince her most intractable patient that she can continue portraying reality.

Simón, who has had it with Olivia's attitude, hires a lawyer who is a friend of Noemí's to help him with custody. This causes an escalation of tension between Simón and Olivia. Luigi loses the rent money due to gambling debts. He tries to control his addiction and discovers that it is not easy. Gabriel is taking antiretroviral treatment for the cut that was made while operating on a patient with HIV.

During his shift, Gabriel is kidnapped in a car and dragged to his brother's workshop: one of his men has been shot twice. Petru demands that he save his life. Simón and Olivia come to an agreement without lawyers involved and set off Noemí's alarms. Almu, separated from the hospital, forbids Nico help him again. In parallel, he gets into more trouble.

One of Petru's men leaves Adrian, half dead, lying at the door of the ER. It is discovered that someone from the hospital has operated on him illegally and an internal investigation is opened that puts Gabriel, Almu, and Berta on high alert. Olivia tries to blend in with her young, liberal classmates. Sandra discovers a personal facet of Darío that makes her question the future of their relationship.

Almu organizes a party to celebrate his birthday, but above all his separation from Nico. Olivia throws herself into living the youth she never had. Almu's party is an opportunity that he doesn't plan to miss. Tobias tries to convince Blanca that he is willing to settle down for her. Darío publishes a nude portrait of Sandra in a prestigious magazine. She dies of shame.

Code red in the hospital. The urgency is filled with children. A kamikaze who was driving drunk has hit a school bus. Olivia concentrates on work until she discovers that the crashed bus is the one her daughter uses to go to school. Luigi faces a litmus test on his last day as a resident of Los Arcos: the kamikaze is the man who killed his wife.