16-year-old Karl breaks through the ice while skating with his mother Sabine on a secluded mountain lake and threatens to drown. dr Martin Gruber and his brother Hans are able to pull Karl out of the icy water at the last second. But during the follow-up examination in the hospital, Martin has to discover severe liver damage in addition to severe hypothermia. Karl urgently needs a new liver. Fortunately, this organ also accepts living donation. This means there is a good chance that a direct relative will come into question as a donor. Unfortunately, Sabine has to destroy this hope. In order to save the life of her beloved son, she is forced to confide in him her darkest secret: she kidnapped Karl as an infant. dr Martin Gruber must now find the biological parents in order to save his patient's life. But that's not so easy: Karl is not ready to betray the woman who raised him for 16 years.

Martin Gruber seems ready for his "new life". He has made a truce with Anne, left the Gruberhof and has moved into a small apartment. But he is and remains a doctor with body and soul, which is why he devotes all his heart and soul to his little patient Leo Wimmer. The baby, who is only six months old, has high fevers again and again, his parents Jakob and Sabine are very worried. Leo's laboratory values don't look good either. Martin suspects an inherited immune disease, but a genetic examination of the parents does not provide any findings. But one Surprising realization: Jakob is not Leo's biological father. Kathi Wimmer, Leo's adult sister, is visiting Ellmau to introduce her parents to her new boyfriend Tobias Ritter. When Sabine and Tobias see each other, they are both visibly shocked. They already have each other met once – nine months before Leo was born Sabine wants to remain silent, but Martin is sure: Only the biological father ka nn still save the baby. And Sabine has to tell the truth about that. Because Kathi and her father Jakob still have no idea about Sabine's secret. Martin's daughter Lilli is still not sure whether working on the farm or in the practice is right for her and therefore decides to divide her time up in the future. Business at the Gruberhof is finally starting up again, not least thanks to Anne's zest for action. But Hans and Anne have only been business partners for 24 hours before they are at odds again. And of all things, Martin, who was called to help by mother Lisbeth, is now supposed to mediate between the two stubborn heads. He's not only completely tied up in professional matters, but also in matters of love. Because Rike absolutely wants to spend more time with him – just like her son Lukas. At a meal together, the situation with the teenager escalates. Although Lukas later apologizes to Martin at his mother's urging, his joy is limited when Rike suggests spending a few days together as a couple. Martin's friend Kahnweiler, on the other hand, would be happy if his Vera would finally get in touch again. She's been hiding with a friend for a week because she wants to clear up a few things. Does that mean the end for the two?