Ep 1-01 & 1-02 Serenity (Pilot)
 

Flashback: A bonding between Mal and Zoe takes place during the Unification War.
The present: The crew of the Firefly class vessel Serenity is eager to rid themselves of an easily traceable cargo they salvaged from a vessel adrift in space. They are completely unaware that a passenger has brought even more dangerous cargo aboard.

This is a great episode. It has a good plot to it and introduces us to the main characters and principle bad guys, the Alliance and the Reavers. It also shows us what kind of people our main characters are, people doing whatever they can to survive in a futuristic society. I never saw this show until it was on DVD because of work but I knew as soon as I saw it that I was gonna like the show. :D