Rudi Kranzow has made a name for himself in the red-light district of St. Pauli, and his "Blaue Banane" is one of the most exciting strip clubs in this hot spot. Here, Lajana, temptation incarnate, dances while ex-boxer Sugar, Kranzow's loyal bodyguard, kicks out uninvited guests. Mizzi, an aging prostitute who is an excellent cook, and Karin, alias Karl-Heinz, a transsexual with a big mouth, are part of the furniture. When Kranzow, nicknamed Würfel-Rudi (Dice Rudi) because of his passion for gambling, is unable to pay his gambling debts, fish wholesaler Graf, who controls the scene from behind the scenes, reaches out for the "Blue Banana."

Robert Kranzow dropped out of law school to take over his father Rudi's strip club in St. Pauli after Rudi was left in critical condition following an attempted murder. To pay off Dice Rudi's crushing gambling debts, Robert has set up a catering service with bodyguard Sugar, prostitute Mizzi, and transsexual Karin. But Rudi's promissory note is now in the possession of magician Dirk, who does the dirty work for real estate mogul Dr. Schmidt-Weber and is doing everything he can to bring Robert to his knees.

Rudi is finally discharged from the hospital and takes over the business at his strip club, which is now called "Blue Banana." He falls in love with the new singer Julia—who his son Robert also has his eye on. Tensions between father and son escalate when Robert narrowly escapes an assassination attempt and Rudi wants to send his son back to Munich for his own protection. Rudi suspects the "Count" and pays his powerful adversary a visit to threaten him.

The shy singer Julia discovers her hidden talents as a stripper, and things finally start looking up again for Rudi and the "Blue Banana." But real estate mogul Schmidt-Weber, who has acquired the entire neighborhood except for the Kranzow house through straw men, sends his people to sabotage the reopening of Rudi's strip club.

The glamorous reopening of the "Blue Banana" is a huge success, but intrigue causes Rudi Kranzow to lose his license for the time being. He also threatens to lose Julia, because the new star stripper turns to her ex-lover in Munich in disappointment, as Rudi demonstratively ignores her for fear of becoming too attached. Rudi is and remains a gambler: when the "Count" offers to gamble for the Kranzow house, he cannot say no.

By chance, Robert exposes the treacherous magician Dirk as the murderer of the stripper Lajana, whereupon a dramatic turn of events looms in the power struggle in St. Pauli. Together, Rudi and the Count discover that the corrupt construction magnate Schmidt-Weber wanted to play them off against each other in order to take over the entire neighborhood. Schmidt-Weber loses his nerve and hires Chinesen-Fiete, a dangerous killer who wants to settle the matter his own way.