Liberty, By Garrison Keillor

When a book about human failure is solely populated by an amiable cast, or what Liberty's flyleaf refers to as "good, loving people who drive each other crazy", it's commonplace to praise a writer for his generous attitude to his characters. That's a reasonable way of viewing the world Garrison Keillor has created in his Lake Wobegon stories, and this latest instalment is no exception. Only a heart of the coldest stone would not root for Liberty's Clint Bunsen – late-middle-aged auto mechanic, parade organiser and aspirational philanderer - from the first page.

There is another response, though: to readers not fully paid-up members of the Keillor fanclub, all this good humour can begin to seem just the littlest bit suffocating. As we follow the Wobegonian cast of ill-tempered but loveable eccentrics from front porch to motel room in the build-up to the town's Fourth of July parade, which will be Clint's last in charge and which acts as the book's climactic set-piece, it occasionally becomes infuriating not to be permitted to find even one straightforwardly dislikeable. Blanket compassion is just as pat a response to such a rich tapestry of irascibility and intolerance as a kneejerk rush to judgment.

Partly, that monotony is relieved by Clint himself, who, as an unapologetic Republican with little time for the sort of neighbourly warmth Keillor implicitly advocates, acts as a useful pressure valve. Partly, too, the controlling folksiness is leavened by the sharp tang of regret that suffuses the novel. As our hero prepares for the parade, and wonders why no Wobegonian ever appreciates his gargantuan efforts, he embarks on a reckless affair with a woman half his age that prompts a bleak re-evaluation of a whole life accidentally spent in middle America.

"I am a prisoner," thinks Clint, whose self-perception is also rocked by the results of a DNA test that informs him he is not from the dour Northern European stock he has always assumed: "I am a Hispanic American who laboured for years under the burden of Norwegianness and now I am reconsidering the whole deal. Sixty years old: last chance to have a life." And he composes a song to himself: "Thinking of a girl I love and what my life could have been/How did I wind up in this army of disappointed men?"

The consoling answers Keillor offers are familiar; the converging catastrophes of his finale are, likewise, utterly predictable. Luckily, his voice and Clint's are charming and wry enough to get away with it. Liberty's quiet nostalgia is hard not to enjoy; just don't expect Keillor to let you know who to blame for the life you haven't lived, or how to find your way back to it.