Bethge promises his mother to find his sister. But detectives in Weesenburg aren't keen and block his activities. They suspect a revenge act by mobsters, investigating Barbaras ex-husband instead - causing a Bethge family rupture.
No trace of Barbara, her family turns to the public. But when young detective Anna Bach takes on the files, her hunch is Jürgen Becker, a gardener: He was one of the last seen with Barbara and provided a shady alibi, without being asked.