Prince Zhemchuznïy's daughter Natalya is betrothed to the elderly Molchan Mitkov. Her lover, Andrey Morozov, plans to join the oprichniki, the Tsar's bodyguards, who have undoubted privileges of money and women. He confides to the oprichnik Basmanov that Zhemchuznïy has taken all his family's land and possessions. Natalya hears the men, but they have gone before she can reach them. She sits in sadness, comforted by her nurse and the women of the household. Andrey's mother, in spite of her troubles, disapproves of the oprichniki and the Tsar's favourite Basmanov. Without telling her of his intention, he joins the oprichniki, inducted by his father's enemy, the commander Prince Vyazminsky. In the third act Andrey's mother and then Natalya are appalled to find Andrey an oprichnik, and Basmanov urges him to seek dispensation from his vows from the Tsar. At the wedding of Andrey and Natalya, the Tsar calls for Natalya to be brought to him. Andrey opposes this, but in vain. Cursing the Tsar, he is arrested and executed in the sight of his mother, through the agency of Vyazminsky, who thus has his own revenge.

Tchaikovsky, always critical of his own work, positively disliked his opera The Oprichnik. Use is made of Russian folk-song in a score that re-used music from his first opera The Voyevoda (The Provincial Governor).