So Far Gone by Jess Walter

From the #1 bestselling author of Beautiful Ruins—and in the propulsive spirit of Charles Portis’ True Grit—comes a hilarious, empathetic, and brilliantly provocative adventure through life in modern America, about a reclusive journalist forced back into the world to rescue his kidnapped grandchildren.

Rhys Kinnick has gone off the grid. At Thanksgiving a few years back, a fed-up Rhys punched his conspiracy-theorist son-in-law in the mouth, chucked his smartphone out a car window and fled for a cabin in the woods, with no one around except a pack of hungry raccoons.
Now Kinnick’s old life is about to land right back on his crumbling doorstep. Can this failed husband and father, a man with no internet and a car that barely runs, reemerge into a broken world to track down his missing daughter and save his sweet, precocious grandchildren from the members of a dangerous militia?
With the help of his caustic ex-girlfriend, a bipolar retired detective, and his only friend (who happens to be furious with him), Kinnick heads off on a wild journey through cultural lunacy and the rubble of a life he thought he’d left behind.