On the stairs Natasha ran into her neighbor from across the hall, Baron Wolfe. He was somewhat laboriously ascending the bare wooden steps, caressing the bannister with his hand and whistling softly through his teeth.

“Where are you off to in such a hurry, Natasha?”

“To the drugstore to get a prescription filled. The doctor was just here. Father is better.”

“Ah, that’s good news.”

She flitted past in her rustling raincoat, hatless.

Leaning over the bannister, Wolfe glanced back at her. For an instant he caught sight from overhead of the sleek, girlish part in her hair. Still whistling, he climbed to the top floor, threw his rain-soaked briefcase on the bed, then thoroughly and satisfyingly washed and dried his hands.

Then he knocked on old Khrenov’s door.

I really do not understand the ending.