Department S

The entire workforce of a chemical plant call in sick on the same day - yet the next day the neighbors claim that it seemed like a perfectly normal workday, with vehicles coming and leaving, etc. The local police don't know what to make of it and hand it over to the Department.

The detectives soon realize that the workers' 'sickness' was due to poison, but that one man did show up for work anyway - and he is found murdered. So what was going on at the factory that particular day that's worth killing for? The secretary is also missing since that day, and the Department's investigators try to locate her. When they do, they discover that this case has much wider implications, which also include a newly build nuclear power plant...