A stranger asks Thorsten Falke for a meeting. He hopes, he says, that the Commissioner will deliver on a promise that is more than 20 years old and help him out of an emergency. Since the stranger demands a promise without, however, revealing the further circumstances, Falke refuses. Shortly afterwards, the man is pulled dead out of the Elbe. As it turns out, he had lived under false identities. To find out who the man really was, Falke and his colleague Julia Grosz have to delve deeply into their own past. And even with the man they finally suspect, nothing seems to be as it seems