Old John Carstens sells his marine‐equipment firm to Lafrenz, unaware it’s now a fuel‐smuggling front. Living above the showroom with daughter Hanna and son Jochen, he resists Lafrenz’s pressure. When Hanna falls for bargeman Oschi Rasmus, Lafrenz demands John either give up Hanna or settle his debts. John defies him and dies. Oschi clears John’s debts, but Lafrenz soon plots against the young couple.