SPOILER POLICY: Please place behind spoiler cuts anything revealing major plot points from the movie "Serenity." Additionally, if you are talking about a BIG plot point in the show (I will make a list - behind a cut) - please consider cutting it as well.
Now, list of things I personally consider to be big enough that I wouldn't tell anyone who hadn't seen the show:
1. the fact that Kaylee doesn't die in "Serenity"
2. Jayne's betrayal of Simon and River and Mal's reaction
3. the triumphant return of the BDH in "Safe"
4. the fact that River is on Jubal Early's ship in "Objects in Space"
These are just the few I could think of off the top of my head.
queenginny, if you would add this policy to the userinfo I'd be most grateful. I'd do it myself but I'd be afraid I'd put it somewhere not aesthetically pleasing and without a cleverly tied-in quote, so I'd like you to do it if possible.