A Bag of Hammers revolves around the friendship of two charming grifters, Ben and Alan, played by Jason Ritter and Jake Sandvig. Ben and Alan have built a successful though larcenous business, posing as car valets, only to steal the vehicles instead of parking them. Because of their less-than-ideal childhoods and a "job" that allows them to remain likeable boyish rogues well into their 20s, their penchant for crime is almost forgivable. However, everything changes when they meet a twelve-year-old boy named Kelsey. Neglected by his mother, Kelsey is drawn to Ben and Alan and they to him - eventually, Kelsey becomes part mascot, part protégé. His presence ultimately forces Alan and Ben to choose between a life of crime and fun (an extended childhood) and the opportunity to grow up and deal with the emotional consequences that come with it.