When the pictures from Bergamo in Italy go around the world in spring 2020, even non-medical people know what the word pandemic means. The previously unknown Coronavirus is spreading rapidly across the planet. Four days later, exit and contact restrictions also apply in Germany. Since then, the life of the Konstanz intensive care physician Dr. Carolin Mellau and her family on their heads. The female doctor becomes a member of the crisis team and is on duty around the clock to prepare the clinic for the impending emergency. As an anesthesiologist intubating those infected with COVID-19, she herself carries a high risk of infection. Meanwhile, her husband Stefan has to cancel his concerts as a musician, is no longer allowed to teach his music students and is suddenly sitting at home without an income. Teenage daughter Luzy is not allowed to see her Swiss boyfriend because the border is closed. She and brother Tim cannot go to school. But the worst case for the family is yet to come.

An excursion boat on Lake Constance. Good-humored passengers celebrate at a costume party. In the middle of it all is Elena Barin on the day before she takes up her post as head of department at the Constance criminal investigation department. She is traveling as a tourist - until the moment she notices a weapon on a passenger.