In Chris Paines's provocative documentary, four contenders from different sides of the business world compete to rescue the electric car from obscurity after the auto industry had abandoned it in the early 2000s. Manufacturers from GM, Tesla, and Nissan, and an entrepreneurial mechanic called "Gadget" vie to revive an energy source that dates back to the start of the motor vehicle industry and fared pretty well until it was superseded by the internal combustion engine. Much of the film involves cold facts and crunched numbers as it examines historical failures and more recent debacles, including cases of financial ruin and even arson. But Paine (following up his Who Killed the Electric Car?) sustains interest by providing what seems an insider's look at schemes, both legitimate and sleazy, cooked up behind closed doors. In the end, Revenge is sweet, and Paine's outlook is positive, with a prospect of clean air and even an end of oil dependency.