The second act of The Cherry Or-chard is one of the most sustained passages of theatrical perfection ever written. And by any conventional standards, it is one of the worst written. Charlotta tells us her life story, with no build-up and even less follow-through, then walks off. Yepikhodov sings, then walks off. The servants flirt then flit away. The householders wander on. Lopakhin tries to force the gentry to save their house, fails and sits down. Lyuba pours out a torrent of soul-charged confession, to which there is no response. Music is heard and spirits lift. Firs, the wrinkled retainer, stumbles in, witters about the past, then falls silent. The children tumble on, spilling joy in their path, then go quiet. Trofimov rages about the forthcoming revolution, but is silenced by the sunset. A distant wire snaps in a mine shaft and chills everyone's spirits. The characters drift away, leaving two young lovers trembling on the brink of a first kiss. They dash off. Afternoon passes to moonlight; frogs croak and crickets chirrup. There is no pattern, no order, no consequence, and yet it is breathlessly transfixing throughout.

The act is a nightmare to rehearse, partly because of the lack of pattern, but mainly because of the lack of causality. Things happen, then stop. There is no this-to-that, nor any here-to-there. Without these things, actors feel very exposed. Yet something glues it all together, a something that Rosamund Bartlett nails beautifully in her new book. In a word, it is landscape.

Chekhov had an extraordinarily acute understanding of the effect of the outside on any human's inside. On sunny late afternoons, as summer peaks and falls, if we sit in a place looking out over a blaze of cherry blossom, we do start to talk. Our conversations are not the aggressive, territorial banter found in so many modern plays; they are between us and ourselves, and between us and God, a God expressed by Chekhov in the landscape he understood so completely.

Bartlett recounts Chekhov's life through the prisms of all the places that mattered to him. She puts us on a tour bus and drives us through 19th-century Russia, starting in the Taganrog of his childhood, taking us through Moscow and Petersburg, Siberia and the Cote d'Azur, Yalta and the Black Forest where he died. She focuses on recreating each place in devoted Chekhovian detail, animating her scenes with human comedy. Her invocation of Melikhovo, where I spent a heavenly day roughly 15 years ago, is spot on. And the contrast she achieves between the frozen wastes of Siberia and the fussy luxury of Nice is delightful. This is not the landscape of Romantic poetry: there are no rugged rocks and yawning chasms. It is a real landscape, both majestic and petty, peopled by figures who, whether peasants ground down by poverty in Melikhovo or parasol-twirling expats in Nice, are always exceptionally vivid.

If Bartlett does not quite match the skill of her subject, she brings you back to him with renewed excitement. Landscape pulled Chekhov out of himself, away from his worldly cares, into a state of grace. At dawn or at twilight, as light fought with dark, and all the little noises of insects, animals and humans busied themselves with their little skirmishes, Chekhov managed to dissolve himself into the scenes he was watching. Although a fastidiously private man, he had the capacity to become at one with creation, and he recreated this state in his plays and his stories, so that others too, could enjoy it. It is a state Chekhov best expresses at the climax of his short story "The Lady With the Little Dog":

Sitting tranquilly next to a young woman who seemed so beautiful in the dawn light, entranced by this magical setting - the sea, the mountains, the clouds, the vast sky - Gurov was thinking that when you really reflect on it, everything is beautiful on this earth, everything that is, except what we think and do, when we forget about the higher purpose of existence and about our human dignity.

A person - most likely a night watchman - came up to them, peered at them and then went away. Even that detail seemed mysterious and beautiful, too. You could see the steamer from Feodosia arriving, lit up by the dawn and already without lights.

"There is dew on the grass," said Anna Sergeyevna, breaking the silence.

"Yes. Time to go back."

They returned to town.

Bartlett, together with Janet Malcolm (Reading Chekhov) has succeeded in freeing the playwright from the dead hand of conventional, what-happened biography. Because it is structured by place, and not chronologically, the narrative dances about through time. Thus, it will never be a stay-up-all-night book, but as something to dip in and out of, it's a treasure.

Dominic Dromgoole is artistic director of the Oxford Stage Company