The story of the film, in a nutshell, focuses on a trio of pot dealers in Laguna Beach, of which Lively's character, Ophelia, is one.  When the Mexican Baja Cartel comes in to town, the trio refuses to hand over their business, and thus begins a series of violent encounters and escalations that lead to Ophelia's kidnapping and probably a huge amount of brutality.

This image debuted on the official Twitter of Universal Argentina, but would seem to have subsequently disappeared (it's first showed up right here), but now it's everywhere.  The version you see below is courtesy of The Playlist.

Stone and screenwriter Shane Salerno adapted Savages from the novel of the same name by Don Winslow.  Stone apparently jumped all over the material before the book was even released.  He's certainly assembled a formidable cast.  The two leads, ex-Navy Seal Chon and blissed-out Buddhist Ben, are played by Taylor Kitsch and Aaron Johnson.  Their characters are in a shared romantic relationship with Lively's Ophelia, whom they refer to simply as O.  Salma Hayek is playing the leader of the Baja Cartel, with Benicio Del Toro as her most feared and merciless enforcer.  Uma Thurman plays O's mother and John Travolta is involved as a DEA Agent.  Emile Hirsch, Joel David Moore, and newly-minted Oscar nominee Demian Bichir play substantial roles as well.

Savages is currently scheduled for September 28th.