Dr. Heinz Hausner, Professor of Veterinary Medicine, collapses dead on the street: heart attack. What at first looks like a natural death is murder. Dr. Hausner's wife Ines and his lover Uschi Reichert were near the crime scene – neither has an alibi. Meanwhile, a beagle that Hausner examined shortly before his death disappears from the cages of the university. Rex tracks down the distraught dog lady... Richie has chosen Sonja, although Rex is against it. But the pretty veterinarian searches in vain for an undisturbed conversation. Something is constantly coming up. When Moser finally has time for her, it's too late...