"The retired monster" is Nikita Sergeyevitch Khrushchev. "Leonid Vitalevich" is Leonid Vitalevich Kantorovich. This is, I think, the heart of the ending:
When he awoke, beside the steady breathing of Nina Petrovna... out would come the other memories.... The groaning trees in the Western Ukraine in ‘45, when the NKVD hangmen had been at work, and the sight through an incautiously opened door in ‘37 where an interrogator had been demonstrating the possibilities of a simple steel ruler, and the starveling child vomiting grass during collectivisation. And more; and worse. So much blood, and only one justification for it... if it had been all prologue, all only the last spasms in the death of the old, cruel world, and the birth of the kind new one. But without the work it was so much harder to believe.... The garden came no closer, where the lion would lie down with the lamb and all could play at criticism after dinner, if they had a mind to.
He fumbled with the tape machine, and found the RECORD key his son had shown him. ‘Paradise’, he told the wheatfield in baffled fury, ‘is a place where people want to end up, not a place they run from. What kind of socialism is that? What kind of shit is that, when you have to keep people in chains? What kind of social order? What kind of paradise?’ He pressed STOP. Covered his mouth with his hand. And then, since he was tired of fear, of feeling it and of causing it, the retired monster sat very still on the bench by the field, and waited until Kava the rook hopped up onto his knee. A little wind came arrowing across the wheat and swayed the birches over his head. And the leaves of the trees said: can it be otherwise?
And here is the whole thing: