A drop in the number of new cases heralds the end of the epidemic. Will there be a second wave? Anne-Marie is suddenly confronted with several cases of sick people who have had no contact with infected individuals. The team works to solve the puzzle. Sabrina and Juliette sell their first ferret.

Two days before the official announcement that the epidemic is over, the infection of two little girls brings Anne-Marie back to square one. The epidemiological investigation resumes, but the girls are uncooperative. Will Nelli get them to talk and prevent COVA from claiming more victims?