In an ancient castle in the south of Sweden, work on a series of television programs for the “Summer Palace” project is being completed. On the last night, on the eve of the national holiday Jan's Day, the creative team celebrates the completion of filming. After a wild party in a mobile television studio, program presenter Michelle Karlsson is found murdered. The death of the public's favorite TV star causes a loud public outcry. A reporter for one of the major newspapers, Annika Bengtzon, is tasked with following the investigation and keeping readers informed. Annika dives even deeper into the backstory of the tragic incident when she learns that her close friend was at the castle on the night of the murder and is the main suspect. Now the journalist’s main goal is to figure out which of the thirteen participants in the events is the true criminal.