Hamburg, February 1962: thanks to the economic miracle, people are visibly better off. The future German Chancellor Helmut Schmidt is Senator of the Interior, and upcoming world stars are playing in trendy music clubs in St. Pauli. The weather is as bad as usual. Hardly anyone suspects that there is more behind the masses of water whipped up by the storm than usual. Susanne Lenz (Natalia Wörner), who warns of the storm “Vincinette” at the maritime weather office, seems overly cautious to her colleagues.

For Katja Döbbelin (Nadja Uhl), Saturday, February 17, is certainly not going to be like any other day. That’s when the young nurse wants to marry senior physician Markus Abt (Jan Josef Liefers). Until then, she has her hands full. There’s the move with her 6-year-old son Philip (Henry Stange) from her parents’ modest home (Jutta Speidel, Elmar Wepper) to Markus’ villa, there’s the wedding dress fitting. In addition, together with colleague and friend Nicola (Bettina Zimmermann), work has to be done at the hospital. Markus also has a lot on his plate. His father, State Secretary Karl Abt (Michael Degen), still wants to dissuade him from the allegedly “inappropriate” marriage – which Markus rejects in no uncertain terms. He loves Katja.
But Markus also has to explain this to Nicola, with whom he has more in common than Katja and others realize. And his job also demands his attention. After a storm on the North Sea, a colleague’s son goes missing – Markus has to take over on his bachelor party of all days. After all, sick people have no respect for doctors’ family celebrations.

Jens Urban (Götz George), for example, is facing an operation. Even the surprise visit of his son Jürgen (Benno Fürmann) does not reconcile the embittered farmer. Jürgen has been at sea for years. But he knows Markus – and Katja very well. She was his great love, he was hers and still wonders why she never answered his letters. Now he finds out about their wedding. Katja and Markus have dinner with the best man and her parents, the down-to-earth Döbbelins, the suave Karl and the elegant Karin Abt (Gaby Dohm).

Jürgen’s arrival takes Katja completely by surprise. She has never seen the letters he talks about. She had long wondered why he had left her – until she decided to forget him. Katja’s mother puts an end to their reunion. She sees the long-awaited good match that the doctor Markus means for her daughter and grandson in danger. But Katja’s brother Stefan (Gil Ofarim), whose long hair causes offense almost everywhere, senses that Jürgen’s arrival has changed something for his sister.

On Friday, with the wind getting stronger and stronger, the wedding reception takes place at the “Hansekroog” in Hamburg-Wilhelmsburg. Stefan is there, even though his guitar band has a big gig lined up. Only Katja’s uncle Alexander (Heiner Lauterbach) is missing. Adverse weather conditions keep him at his workplace on the first German oil rig. Nobody on the mainland knows what danger the storm
is putting him in…

Jürgen has given up his plan to set sail again and has taken a room with the landlady Lotte (Hannelore Elsner). Since his reconciliation with his father, he knows that it would be wrong not to talk to Katja.

His appearance at the hen party causes a stir. Katja’s doubts about her future plans grow. Jürgen is not unaware of this. An argument between Jürgen and Markus goes off without a hitch.

Now, of all times, Markus is called in for surgery. Jürgen is out on his motorcycle and Katja is still at the Hansekroog with her son. All of a sudden, all their thoughts and worries fade away. Because the lights go out, sirens wail. The flood is coming…