Social workers Freja and Martin arrive on an island with a group of juvenile delinquents. But the quarrels among the adolescents are not the ones causing problems. When two bodies are discovered in a stranded sailboat on the North Sea island of Sløborn, growing signs indicate that the bodies are carrying a deadly disease. At first the islanders are too involved in their own personal problems to comprehend the grave danger. Then the fatal virus invades the seemingly idyllic island deeper and deeper – and slowly takes complete control of their lives.