Former investigator Tokarev serves as the head of the fire department's guard, leaving police work in the past. His childhood friend Kolosov is in the pharmaceutical business and sells expensive medical equipment. One day, one of Tokarev's colleagues becomes disabled due to a broken breathing apparatus, which was supplied to the fire station by his friend's company. In an effort to understand the situation, the former policeman comes to a friend and finds himself in the very center of a criminal drama: Kolosov is killed, and his wife becomes the main suspect. Before his death, the businessman puts his adopted son Denis to work in the fire department. Now Tokarev and Denis will have to get used to each other and together not only put out fires, but also investigate the murder of Kolosov...