Beginning with a flashback to six years prior to the start of the series’ events, back when Malcolm Reynolds (Nathan Fillion) and Zoë Washburne (Gina Torres) were rebel soldiers in the war against the Alliance. The show jumps forward to the “present” where Mal and Zoë are now part of a salvage crew with Jayne Cobb (Adam Baldwin), Kaylee Frye (Jewel Staite), and Zoë’s husband Hoban “Wash” Washburne (Alan Tudyk) on the Firefly class spaceship Serenity.  The crew is running a salvage operation on a deserted ship but are forced to flee with the cargo when an Alliance cruiser show up.

Their fence, Badger (Mark Sheppard) refuses to buy the cargo so they head off to the rim worlds after picking up three passengers: Shepherd Book (Ron Glass), Dr. Simon Tam (Sean Maher), and Dobson (). En route someone on board – an undercover Alliance agent – signals the Alliance and arrests Simon. It soon becomes clear the agent plans to take the whole crew in. He shoots Kaylee () before being captured, and Simon forces Mal to flee in return for his doctoring services. When Mal investigates Simon’s cargo he finds a naked woman (Summer Glau) packed in a create for transport. The crew soon learns who she is, and why Simon is transporting her like cargo.