This story follows the character Andrey Kovrin, a Russian scholar who is seemingly brilliant. In the beginning of the story, Kovrin is overworked and his nerves are off. He is invited to take a break in the country at the home where he grew up. The place is gorgeous, with expansive gardens and orchards - it is the lifework of Yegor, his former guardian, who lives and works there with his daughter, Tanya. When Tanya and Kovrin were children, Yegor became Kovrin's carer when both his parents died. Both think very highly of Kovrin and are very excited about his arrival. Kovrin learns how much work it is to take care of the garden, and develops a deep appreciation for it. Then he starts seeing a black monk, whose appearance borders on the supernatural, and begins to question his sanity. The black monk convinces Kovrin that he is chosen by God for a special purpose - that he has the power to save mankind from millennia of suffering using his genius, and that his recent ill health of late is inevitable for someone making such noble sacrifices.
The old man expresses to Kovrin that the only man he could trust to marry his daughter is Kovrin himself, convinced that any other man would take her away and his life's work would fall into ruin. They marry and, in time, Kovrin's wife notices his hallucinations, since he often converses with the black monk. She "cures" Kovrin over time, but he becomes convinced that without the black monk's "guidance," he is doomed to mediocrity instead of genius. He becomes bitter and antagonistic towards his loved ones, and eventually the couple splits up. His physical health deteriorating rapidly because of tuberculosis, he moves in with a woman who takes care of him. The story ends with Kovrin experiencing one final hallucination while he hemorrhages; the black monk guides him toward incorporeal genius and he dies with a smile.