30-year-old Max works as an emergency doctor in a Berlin hospital. He has been in love with the attractive Coco for a long time, with whom he shares a well-kept apartment. Coco jealously defends the relationship, while Max feels restricted in his freedom. One day Max dials the wrong number and falls in love with a voice on the other end of the phone that says only one word: "Hello". On nightly forays through the city, Max looks for the woman who owns the voice and hopes to escape the close proximity of Coco. In a billiard salon he finally meets Marie, who is accompanied by her partner Kurt. Shortly afterwards, Marie and Max are involved in a car accident that causes them to hug each other and make love in the rain on the street. When Max and Coco later have a party, Marie and Kurt are guests at the door. As a result, Max and Marie try to couple their respective partners together.