Karenin goes to see a famous Petersburg lawyer. The lawyer is occupied when Karenin arrives at his office, but Karenin sends his card in and the lawyer comes out to meet him straight away. The lawyer tells Karenin that he is familiar with Karenin's name and his work in public office.
The lawyer goes over Karenin's various options, as Karenin makes it clear that this is a preliminary consultation only. The lawyer is visibly delighted at Karenin's confession of his wife's adultery. He seems to feel real joy in Karenin's suffering.
The lawyer suggests, instead of actual divorce, adultery by mutual consent. But Karenin says that such a thing would be out of the question for him.
The lawyer then says that if Karenin's want to get her on adultery, he needs proof from actual witnesses to make your case in court. Karenin doesn't seem to like that idea much either.
Karenin says he will inform the lawyer of his decision by letter.