More than two million followers online want to see how the "Paleo Girl" at Lake Constance brings the Stone Age back to life. One morning, as Katrin Baumann—Paleo Girl's real name—tries to push a prehistoric boat into the lake, she is knocked unconscious from behind and abducted.

The body of a competitive rower who died during training has disappeared from the funeral home. His young widow, Leni Senger, is stunned.

Paul is participating in an open-water swim. In the middle of the lake, a swimmer next to him gets into trouble and dies. The deceased is businessman Max Behringer, who made many enemies with a wind farm project on the Swiss Seerücken.