- "Target the Reavers. Target the Reavers! Target everyone -- Somebody fire!"
- ―The Operative, ordering the Alliance fleet to attack the approaching Reavers.
The Alliance fleet was originally in orbit of the planet tasked with capturing the Serenity, in order to prevent Malcolm Reynolds from delivering the Miranda recording to Mr. Universe for broadcast over the Cortex. Unbeknownst to them, Mal had lured the Reavers after him, which attacked the Alliance ships and continued to pursue Mal's ship.
In the ensuing chaos, Serenity was able to slip past the blockade and penetrate the planet's atmosphere. It was pursued by a Reaver ship that eventually was able to hit it with an EMP that forced a crash landing. Only Hoban Washburne's superior piloting ability saved them from certain destruction.
Wash was able to land Serenity at the entrance to Mr. Universe's home, though the ship was badly damaged. The Reavers followed, and killed Wash by shooting a harpoon through the ship's forward viewport. The rest of the crew ran for the relative safety of the bunker.
There, the crew found Mr. Universe dead and his equipment destroyed, but he had survived long enough to record a message in his love bot informing them of the location of a backup transmitter. Zoe and the rest of the crew volunteered to hold off the Reavers to allow Mal a chance to get to the transmitter and broadcast the recording.
Mal moved deeper into the facility while the others put together a makeshift barricade at a strategic location. The Reavers attacked in large numbers, and it was soon apparent that they would not be able to hold. Zoe suffered a critical wound to her back that injured her spine, Kaywinnet Lee Frye was hit by a poisoned dart, and Simon Tam was shot.
The crew retreated into a corridor and attempted to seal shut a set of blast doors to hold off the Reavers, but the mechanism to do so was outside with the enemy. River Tam leaped through the door and closed it, trapping herself with the Reavers.
While this was happening, Mal located the transmitter and was preparing to send out the recording when he was again attacked by the Operative, who had survived the space battle as well. A vicious fight ensued. Mal barely emerged the winner and sent the Wave, forcing the Operative to watch the Union of Allied Planets experiment with G-23 Paxilon Hydrochlorate.
The blast doors began to open, and the crew, prepared for its last stand, was shocked to see River, drenched in Reaver blood and standing alone in the doorway. At that moment, the wall behind her was demolished with harpoons and Alliance troops stormed in. They requested permission to fire from the Operative, who ordered them to stand down, saying the mission was finished.
The Alliance's original mission is a failure, as the Serenity managed to slip past the blockade and thus get the Miranda recording broadcasted using the backup transmitter that the Alliance wasn't aware of. However, they did manage to defeat the Reaver fleet despite significant losses, which would mean that attacks by Reavers on colonies has effectively ceased or drastically reduced.
On the Reaver side, it is their first ever battle with an organized military force, and also their first major defeat.