Zurich drug agent Herbert Strähl dreams of making a big catch. Yet the only fish he manages to catch is the piranha in the aquarium tank he has at home. He laboriously persists in grappling with small-time dealers and junkies while being left in the lurch again and again by his colleagues Ruedi, Dani and Marco. Strähl hides his loneliness and his yearning for love behind fits of rage, amphetamines and yelling until his choleric temperament finally becomes his undoing: as he's conducting a house search, a junkie jumps out of the window. Strähl is suspended. And that's just the start of his problems. Suddenly Strähl finds himself at the mercy of two junkies: the soccer fanatic René and his girlfriend Carol could exonerate him with their testimony. Strähl's attempts to persuade them fail in face of Carol's stubbornness. In desperation, he ends up raiding the small-time dealer Beko and stealing from his stash of heroin to get René and Carol to relent. This sets off a chain of events that brings the big catch within reach.