Midway through "A Perfect Spy," John le Carré's brilliant 1986 novel about a disloyal British intelligence agent, his morally flexible protagonist faces a problem that leaves him "bursting with a sense of righteous duty." A similar compulsion drives the conflicted spy in "Silverview," apparently le Carré's final novel.

Le Carré, the author of "Tinker Tailor Soldier Spy" and other espionage masterworks, was 89 when he died last December. "Silverview" was among the items he left behind. In an afterword, his son Nick Cornwell says he promised that he'd shepherd the manuscript to publication. Readers will be glad he did.

The action unfolds in coastal England, near erstwhile bomb-test sites. The death-haunted terrain is an apt backdrop for a portrait of an indignant spy bent on punishing Britain for its "romp through the wild woods of colonial fantasy."

Edward Avon, suave and "60-something," lives at an estate called Silverview. Cultivating a semiretired vibe, he starts hanging out at a touristy bookstore. In no time, he talks Julian Lawndsley, the shopkeeper, into a casual collaboration — they'll sell classics in the store's basement. Edward promptly starts using his new partner's internet service to re-establish contact with old comrades.

For decades, we learn, Edward was an agency asset in the Soviet bloc and the Balkans, "enduring so many of life's hells." But he turned against Britain and America after the countries mishandled information that might've stopped heinous acts during the Bosnian war. His recent communications suggest he's trying to undermine Britain's foreign policy.

Stewart Proctor, a domestic security investigator, is assigned to investigate Edward, a tricky assignment given the latter's private life. Edward's gravely ill wife, Deborah, is one of the agency's top Middle East analysts, and she seems to have a tenuous grip on valuable secrets.

This is a satisfying novel with some obvious but minor flaws. Le Carré's prose is occasionally bloodless — when a character dies, "her doctor certified life extinct." The romance between Julian and Edward's adult daughter feels rushed and artificial.

Much more often, though, this is an intelligent, mournful, wry delight. A funeral scene featuring a flimsy biodegradable casket — "If you touch the handles," an undertaker says, "you will find yourselves going home with them" — summons a morbid laugh. The book's rueful tone is captured in a conversation between two experienced agents. Says one, "We didn't do much to alter the course of human history, did we?" The other doesn't reply. They both know the answer.

A former spy himself, le Carré was increasingly critical of America's and Britain's interventionist foreign policies. Perhaps his estate is sitting on another unpublished gem that we'll see someday. If not, this is a suitable end to a storied career, a low-key thriller with a brain and a conscience.

Kevin Canfield is a writer in New York City.

By: John le Carré.
Publisher: Viking, 224 pages, $28.