Katie Kitamura's debut novel, "The Longshot" (2009), was a knockout character study of two men, a fighter and his coach. Three lives lay at the heart of her follow-up, "Gone to the Forest" (2013), with Kitamura tracing the tension between a father and son when a young woman arrives at their home. "A Separation," Kitamura's latest novel, essentially revolves around one character, a woman who, while "dismantling the edifice of a marriage," discovers unexpected truths about herself and the man she loved.

After five years of marriage, the woman — our nameless narrator — and her husband, Christopher, have decided to split. For the time being, it is a secret between the two of them. Six months into their separation, she receives a call from her anxious mother-in-law, telling her that Christopher is missing in Greece. Pretending to be the worried wife, the woman flies out to track down her estranged husband — and ask for a divorce.

It is clear from the beginning that this is a novel as much about disappearance as separation. Christopher, the woman learns, was due to check out of his hotel but didn't; he went on a trip several days ago and hasn't returned. She waits for him to show up, explores Greek villages and mixes with the hotel's staff. Eventually she is rocked by two Christopher-related revelations: the knowledge that he is "husband, ex-husband, lover, deceiver," and the news — via the police — that he has been found.

All of which could pass for the bare-bones synopsis of a moderate thriller. But "A Separation" is a different kind of beast. Structurally, it is a book of two halves — the queasy run-up to a tragedy, and the fraught aftermath. Both sections are stylistically ambitious and psychologically rich, as Kitamura eschews pace and puzzles for measured and rigorous inquiry into human motivations and desires.

In lieu of a confrontation with her husband, Kitamura's heroine looks back on her relationship with him, then succumbs to conjecture and imagines his final movements before his vanishing act: He used his "manic charisma" to seduce Maria, the hotel's receptionist; he was killed by Stefano, a local taxi driver and Maria's lover, in a fit of jealousy.

The narrator's fanciful visions prove compelling. Characters become "a physical mass of potentialities." She analyzes body language, reads minds and interprets emotions. Her own emotions are in turmoil, particularly when new flame Yvan calls. How should she feel about Christopher's absence? And is she seeking official separation or possible reconciliation?

"A Separation" is a work of great intensity and originality. Kitamura's Greek setting is off the tourist track, all empty hotels, vandalized churches and wildfire-ravaged landscape. There are deft meditations on the art of translation and the ritual of mourning, and sharp insight into what binds and divides lovers. All is conveyed in strangely long yet lilting sentences. This is the book that elevates Kitamura to a different league.

Malcolm Forbes has written for the Times Literary Supplement, the Economist and the Daily Beast. He lives in Edinburgh, Scotland.

A Separation
By: Katie Kitamura.
Publisher: Riverhead, 229 pages, $25.