A sailboat that had long been reported missing is found drifting on Lake Constance—and on board is a TV starlet who was also reported missing, but who simply cannot remember how she got there. It quickly becomes clear that Nana von Lohe is the daughter of a famous, now-deceased plastic surgeon who ran his clinic on the lake.

Canoe polo is a sport for fit, daring athletes like Paul Schott. When he competes in a tournament on Lake Constance, his colleague Julia and Nele, along with Nele's children Johanna and Niklas and Niklas's friend Josh, cheer him on. But their excitement turns to horror when an opposing player is found floating face down, dead, in his kayak.

The young woman, who was found floating lifeless in Lake Constance and pulled from the water by a fisherman, was apparently the victim of a romantic tragedy. Nadja Koch was strangled by her secret lover, Dennis Böhm, following a heated argument.