From the publisher's website:
Sons of the Gun presents ten new antagonists for players and gamemasters to use in their M&M System roleplaying game. Each of these characters incorporate either guns, weapons trafficking or gun culture into their backgrounds. They include Bandit, Forecast, Gunbunny, Huntsman, Luther, Merchant, Report, Snow Maiden, The Shield and The Untouchable.
In addition to the complete background, stats, and adventure hooks for each character, SotG also presents several Origin-In-A-Box and Story Point sidebars. Origin-In-A-Box presents ideas and concepts derived from the villain's background that can be used to create a heroic origin. Story Point sidebars offer a way for the gamemaster to incorporate elements of the villain's background into their campaign.