The Gamages and the Martinkas despise each other, because of a family feud handed down from generation to generation. Nevertheless, to escape a foster home, newly orphaned Bo Gamage steps off the bus in the California desert to meet his distant cousin Madeleine, a genuine on-the-hoof Martinka.

About his own age, Madeleine wears big sunglasses and calls herself Mzzz Mad. The name sounds to Bo like a mosquito in the air, about to attack. "You one of them ornery Gamages?" she asks. "Where's your horns and your mangy tail?"

Enemies at first sight, they find themselves under the same roof in a ghost town presided over by cantankerous Charlie Martinka, a former cowboy movie star turned prospector. Bo is quickly caught up in a razzle-dazzle of goings-on, which include a wild battle for a missing map, the mystery of the tattooed head, and a daring search for the legendary Pegleg Smith gold mine. And before they know it, Bo and Mzzz Mad find themselves handcuffed -- together!