The crew of the starship Serenity, captained by Mal Reynolds, will do just about anything to keep flying in the wake of the war between the Alliance and the Browncoats, but taking on fugitives Simon and River may have been a big mistake, because now the Alliance is right behind them.

Narrates the background story of Shepherd Book, a crew member of the starship Serenity, who, after being discharged from the Alliance following a failed mission, enters a monastery and decides to come aboard the Serenity as a missionary.