As good as gone / by Larry Watson.

"It's 1963, and Calvin Sidey, one of the last of the old cowboys, has long ago left his family to live a life of self-reliance out on the prairie. He's been a mostly absentee father and grandfather until his estranged son asks him to stay with his grandchildren, Ann and Will, for a week while he and his wife are away. So Calvin agrees to return to the small town where he once was a mythic figure, to the very home he once abandoned. But trouble soon comes to the door when a boy's attentions to seventeen-year-old Ann become increasingly aggressive and a group of reckless kids portend danger for eleven-year-old Will. Calvin knows only one way to solve problems: the Old West way, in which scores are settled and ultimatums are issued and your gun is always loaded. And though he has a powerful effect on those around him--from the widowed neighbor who has fallen under his spell to Ann and Will, who see him as the man who brings a sudden and violent order to their lives--in the changing culture of the 1960s, Calvin isn't just a relic; he's a wild card, a danger to himself and those who love him."--Amazon.com