Poisons or the World History of Poisoning

Young family of Volkov's, Oleg and Katya, move to an apartment they bought and get acquainted with their neighbor, locksmith Arnold Sharapov. Right during a friendly dinner Katya cheats on her husband. Frustrated Oleg decides to drown his sorrows in alcohol, but at the bar accidentally meets Ivan Petrovich Prokhorov, pensioner, whose wife in his time was also unfaithful. In a conversation with the nice old man, Oleg learns that Prokhorov punished his wife by slipping poison into her yogurt. And now Ivan strongly persuades Oleg to also kill his unfaithful wife, using a small collection of poisons which Prokhorov constantly carries with him.