Firefly: Serenity

Nathan, Wash, Zoe, Jayne and Kaylee are the crew of the Serenity. When they discover that the freight they lifted has marks of the Alliance, they take on passengers for respectability and an extra buck or two. Among those passengers are Simon Tam (a doctor), the Shepherd Book and an undercover Alliance agent after Mr. Tam. It all revolves around the mysterious freight that Simon has brought aboard their ship - his sister, River.