Espionage, movie palaces, variety shows, cocaine... While the capital celebrates its upswing, former commissioner Grenfeld has barricaded himself in a rooftop studio. He wants his peace. But as a witness to a brutal murder, he is inexorably drawn into a whirlwind of events that demand everything from him. His only ally seems to be a street boy. Together, they crawl through underground tunnels and climb over the rooftops of the city. He investigates in refugee camps, the first mosque on German soil, and ultimately ends up in a circus – always in search of the perpetrator.