A powerful mobster coerces the crew of Serenity to rob a train full of medical supplies.
Mal and his staff worry that Reavers may have killed the crew of a ship they've overtaken.
Mal accidentally marries a local girl named Saffron who then sneaks onto Serenity to stay with her "husband." But is this some innocent misunderstanding or part of a larger scheme?
Landing on a new planet, Jayne finds himself persecuted by the law and touted as a hero by the residents.
The crew faces a crisis when an engine explosion depletes their oxygen supply.
As a crime lord takes the crew of Serenity hostage, Mal accidentally challenges Inara's date to a duel while at a ball.
Simon and River are captured by border people even as Book is seriously wounded and in need of their attention. When River discerns things about a mute child, the border people accuse her of being a witch. Simon staves off her punishment for enough time for the two of them to be rescued.
While Inara gets her companion physical, Simon thinks of a way he might be able to help River. In order to do so, they will have to break into an Alliance hospital to use the equipment.
The Crime Lord Niska catches up with the Firefly crew to make them pay for the botched robbery. With the captain left in his torturous care, the rest of the crew mounts a rescue attempt.
The crew tangle with a Bounty Hunter who wants River.
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.