Over two million followers online want to see how the "Paleo Girl" brings the Stone Age back to life on Lake Constance. When Katrin Baumann, as Paleo Girl is actually called, tries to push a prehistoric boat into the lake one morning, she is drugged from behind and kidnapped. Julia and Jakob are able to reconstruct this from the evidence after they have discovered the abandoned boat on the lake and, with Mechthild's help, the crime scene. The investigation leads them into a world where the website is constantly busy, clicks and followers are all that matters. Katrin's boyfriend, the nerdy Luka, seems to be more interested in his online profile than in the fate of his girlfriend. He is frightened by the thought that Paleo Girl's big competitor, Janko Reinert, could now gain more fans. With a trick, Jakob is able to expose the true identity of the Paleo hater "Rulaman 666". He had made massive threats to the beautiful Stone Age researcher online. But Fabian Krause has an alibi for the time of the crime. Then events take a turn: While trying to match a tire track, Julia is attacked - and finds herself tied up in a cellar side by side with Katrin. Nele and Paul do not miss how personally Jakob suddenly takes the case. During the investigation, Julia and Jakob grow closer, but they remain professional. While Jakob risks everything on his own, Julia enables Katrin to be freed. The happy ending seems close. But then someone turns out to be a big liar and two others discover their feelings.