Little Ines is found dead on the banks of the Danube. At the same time, girls disappear from an amusement park, but a few days later they are found again: abused and in such shock that they are unable to be interrogated. Inspector Moser suspects a connection between the murder and the kidnappings. The way to the perpetrators leads over the little Birgit. The child has been in a clinic since the kidnapping and is unresponsive. Rex stays in the hospital for days, trying to pull the child out of his apathy. While the dog slowly finds access to Birgit, Commissioner Moser and his team investigate unsuccessfully in the amusement park. Then Rex and Birgit disappear. In the stress of the investigation, Commissioner Moser also has to find a home for himself and Rex. He meets an attractive veterinarian...