River Tam and her brother Simon are hiding out from the totalitarian government that experimented with River's brain aboard a space-freighter. Captained by a down on his luck soldier, the crew of Serenity must take jobs, whether they are legal or not, while trying to avoid the Alliance, and keeping the Tams safe. Then things get out of control and the true extent of River's powers becomes known. At the same time, the Alliance sends a new Operative to make sure that what River knows doesn't get out.