Tracing clues at an abandoned factory site

Before dawn, a report comes in: smoke is coming from a residential area. Firefighters follow the acrid smell of burning. The trail leads to a derelict site. Meter by meter, the emergency responders advance through the vast, abandoned factory grounds and make a very suspicious discovery. Meanwhile, the air ambulance Christoph 9 is called out to a traffic accident with multiple injuries. And on the highway, a vehicle is on fire after an accident. But the emergency lane isn't working – the emergency crews are stuck.