Hidden underground in Oslo, a surgeon and a local civil defence worker start an underground clinic in secret.

Against Leif's objections, Ravn decides to reveal their secret to Vilma's research colleague Unn. Leif offers to help a man who has been separated from his pregnant wife. Leif makes increasing demands on Ravn and Unn.

Leif begins providing patients while Raven makes advances in the treatment of Vilma. But Vilma's daughter Siv starts asking questions.

Leif reconsiders the clinics' managements after an humiliating conversation with his brother. Teo puts himself and the clinic at risk by seeking Marit.

A patient brings a deadly virus to the clinic, and Vilma gets infected. Ravn must make a difficult choice, while Treat works hard to gain control of infection.

With Vilma gone, Raven and Leif must find her before someone else does, leaving Teo completely alone in the clinic.