Potshot by Robert B Parker
Spenser returns; heading west to the rich man's haven of Potshot, Arizona, a former mining town reborn as a paradise for Los Angeles millionaires. Potshot overcame its rough reputation as a rendezvous for old-time mountain men who lived off the land, thanks to a healthy infusion of new blood and even newer money. But when this western idyll is threatened by a local gang, a 21st century posse of desert rats, misfits, drunks and scavengers, the local police seem powerless. Enter Spenser, called in to put the group out of business and establish a police force.