In one of the Bulgarian border areas there is a sudden outbreak of foot-and-mouth disease in its most acute form. The epidemic is spreading very quickly. To stop it, the latest vaccine was delivered from the GDR, but for unknown reasons it does not have any effect on the dying livestock. Meanwhile, Zakhov’s friend, veterinarian Anastasy Bukov, transferred from Momchilov to the Trigrad region, where the epidemic is raging, comes to Sofia for instructions at the Department for combating epizootics. He introduced Avvakum to Dr. Pyotr Toshkov, the secretary of the director of management Irina Teofilova and the typist Khristina Chavova - very nice people. Avvakum even fell in love with Irina, for real. But service comes with service - Zakhov is tasked with figuring out why the proven GDR vaccine is useless for Bulgarian cows. He goes to the department's drug warehouse and discovers the corpse of the warehouse chief, Ventseslav Rashkov...