To be entirely honest, Paramount wasn’t exactly flaunting this synopsis around, so it’s still somewhat secretive. However The Film Stage managed to dig it out of the official press site (guess I should have looked more carefully), and it provides some tidbits of information on the plot:
In Summer 2013, pioneering director J.J. Abrams will deliver an explosive action thriller that takes Star Trek Into Darkness. When the crew of the Enterprise is called back home, they find an unstoppable force of terror from within their own organization has detonated the fleet and everything it stands for, leaving our world in a state of crisis.
With a personal score to settle, Captain Kirk leads a manhunt to a war-zone world to capture a one man weapon of mass destruction. As our heroes are propelled into an epic chess game of life and death, love will be challenged, friendships will be torn apart, and sacrifices must be made for the only family Kirk has left: his crew.
Okay, so there’s still not a whole lot of information to be had here, but at least we know there’s a key plot line here: a manhunt. Scuttlebut around the inter-webs (most notably those way more into Star Trek than I) feels this points to a particular character from the original series. I won’t mention it here because it’s pure speculation, and it would potentially be spoilerific. Feel free to discuss below, however!