The story takes place in the distant future, when human exploration of space has developed to a mature stage. Mel (Nathan Fillion) is the captain of the spaceship Serenity. Every day, Mel drives his "home" through the vast universe. Serenity has nine passengers, with different status and personality. Each of them has a dark past that cannot be told, and they leave the land and board Serenity for different reasons. The only thing the nine people have in common is that they are all "thorns" in the earthly world. In order to make a living, Serenity accepts all tasks that can make money, some of which do not even seem so legal. At the same time, Captain Mel also has to lead his crew to try to escape the federal government.