Comedy Central's ratings grabber Battlebots and the BBC-produced Robot Wars look like harmless, nerd-herding fun. But the early days of the armor-clad contests, hatched by a Star Wars model builder with Parkinson's and funded by one of the producers behind Run D.M.C.'s debut album, shielded viewers from the nastier competition unfolding off screen. Stone smartly avoids too much mechanical mumbo jumbo and swerves through the legal battles that bedeviled the sport, treating readers to portraits of the wacky, passionate tinkerers holding the remote controls. Humans, it turns out, are still more interesting than robots.