The Jack Bull tells the story of Myrl Redding, a Wyoming horse trader who clashes with Henry Ballard, a fellow rancher, after Ballard abuses two of Myrl's horses and their Crow Indian caretaker, Billy. When Judge Wilkins throws out Myrl's complaint, the war he wages to force Ballard to nurse the emaciated animals back to health escalates into a vigilante manhunt, murder and the possible defeat of Wyoming's bid for statehood.
Whenever trouble strikes in one of her relationships, single mother Mary Jo Walker and her daughter, Ava, pack up and move to another city, a routine Ava is tiring of. This time, they are helped on their move to San Diego by trucker Jack Ranson. While Ava settles in, getting a leading part in the school play, Jack starts dating Mary Jo but soon reveals himself to be controlling and aggressive. Mary Jo prepares to flee again, angering Ava.
Davin McDerby is a handsome, irresponsible slacker who arrives in Montauk Long Island for a summer of fun. He has no intention of working too hard and every intention of enjoying himself as much as possible while simultaneously escaping the pressing problems that await him back home in Ireland. Over a summer of car-jacking, pool-hopping, and tequila-drinking Davin and his new found friends discover that they have affected one another causing them to re-evaluate their lives.
