Usually angry wives personally come to the detective agency and ask to catch their husband on a spree at the scene of the “crime.” But for some reason, it was not the deceived wife herself who came running to Vasilisa Selezneva and her boss, Uncle Vasya, but her sister Lisa! She was truly burning with the desire to convict and punish the insidious traitor Arkady, and this immediately alerted the detectives. But work is work - Uncle Vasya quickly spotted the lovebirds and took piquant photographs. And the next day it was discovered: Arkady’s mistress was killed right in her office, and at the crime scene lay one of the photographs taken the day before by Uncle Vasya!