Serenity (2005)

After getting past Reaver space, the crew reach Miranda, an unmarked planet in the solar system. They touch down and realize that the planet's population are dead and decaying. There are no signs of war or terra-forming gone wrong, so the crew follow a weak signal to an abandoned lab. There they witness the horrible secret that the Alliance will kill to keep under wraps. The secret that River saw in the minds of key members of Parliment. 10 years ago, a planet named Miranda was to be the perfect world, the perfect society. The scientists that created Miranda placed "pax" (latin for "peace") into the vents that surpressed emotions. Without those feelings there could be no war or violence. However, the "pacts" surpressed those emotions but it also surpressed others. 90% population stopped breeding, eating, sleeping, and finally stopped breathing. They slowly died off. The other 10% became crazed non-humans, they cut their faces and began eating the rest of the population that were not yet dead. Mal decides that the rest of the universe needs to see the evil of the Alliance. He calls up Mr. Universe and decides to broadcast the signal from his planet where it would each over 30 worlds. However, the Alliance operative tracking River has reached him first and Mr. Universe betrays the crew by telling them that they are safe to touch down on his planet. But the Serenity crew knows that the Alliance would try something like this so they decide to bring some friends. They fire on the floating Reaver ships and they end up following the Serenity ship to where the Alliance is waiting. Serenity gets past the Alliance to the planet below, but a couple of Reaver ships were able to get past the Alliance also. Sitting in the pilots chair, Wash gets impaled and the rest of the crew get holed up in a small room that leads to the generator shaft where they need to broadcast the signal. All the while they are pursued by Reavers. Mal goes down the shaft and the rest try to keep the Reavers back until the signal about Miranda is broadcast. The Alliance operative gets past the Reavers through the vents and down the shaft to stop Mal. The Reavers overwhelm the rest of the crew and they try to seek refuge in a hallway behind them. The blast door gets stuck and they have no means of shutting it unless one of them goes out and closes it from the outside. River decides that its her turn to protect her brother, Simon, and jumps through the hole in the blast door. She throws her brothers medicine bag to him and gets carried off by Reavers. Mal kicks the Alliance operative's ass all over the place and broadcasts the signal. River is NOT dead and kicking some serious Reaver ass. She ends up killing all of them and by that time the Alliance cops bust through a wall. The Alliance operative calls a stand down and lets the Serenity crew go. He realizes that he was fighting for the wrong team and helps the Serenity crew out by fixing their ship. The crew bury Mr. Universe, Shepard Book, and Wash and then flies off into space.