Summer in the Swabian Alb. For more than one Thomas, the father of twelve-year-old Paul, has disappeared without a trace. Together with his best friend Max, Paul not only wants to get to the bottom of this disappearance, but also to find the legendary Ursuline Cave in the mountains, which his father had already been searching for. In the village, Paul is thought to be crazy, which is precisely why he wants to prove it to everyone, especially to his mother Sabine. So the two boys set off into the mountain forests, carrying their father's notes in their luggage. What begins as a carefree excursion turns into a solid adventure.