Having learned of wolves and Lords of Prey moving on Cloud Mountain, the forces of Halfwind Citadel and Terralain march there to offer support to its beleaguered inhabitants. At the same time, Lord Rake and the Forest Guard prepare defenses of their own to contend with the invaders. It soon becomes apparent that the rabbits are badly outmatched, as not one but two massive forces of wolves and birds were waiting to descend on the mountain. Despite this, they lay their plans and prepare for the assault.
Lord Captain Helmer leads a portion of the Halfwind forces to Jupiter's Crossing to launch a preemptive strike against the first force of wolves. After a brief but heated engagement, the rabbits retreat to Rockback Valley where the majority of their force lies in reserve with catapults. Upon seeing the massive number of wolves marching upon them, the rabbits of this reserve force falter. However, Picket Longtreader leads the rabbits of the first engagement to the front, inspiring courage in those who had not yet fought.
The plan worked out between the forces of Halfwind and Terralain was that the Terralain forces would come down on the wolves from the heights above Rockback Valley. However, Bleston deceives the rabbits of the Cause, withdrawing most of his army and infiltrating Cloud Mountain with a small force. Having worked out a deal with Garten Longtreader, Bleston seeks to capture Princess Emma and turn her over to Morbin Blackhawk. This deal would secure a truce between the Terralains and Morbin, while leaving the Halfwind forces to perish in battle.
Bleston's plans nearly succeeds, as with the treacherous aid of Perkinson he takes Lord Rake and other defenders of Cloud Mountain captive and secures Emma as well. However, Picket is able to intervene in the situation thanks to a glider cape developed by Heyward, which he is able to use to reach Cloud Mountain. His arrival allows the Cloud Mountain rabbits to break free and engage the enemy, while Picket himself battles and dispatches Bleston and then Perkinson. At the command of Emma, Picket - promoted to the rank of captain - takes charge of the Halfwind forces, Lord Rake having been killed in the struggle.
Through Picket's work, the Halfwind forces are spared the massacre that had been intended for them and the wolves and birds retreat briefly. However, the second force is only prevented from advancing by a deal Emma made with Garten Longtreader. Hoping to save her friends, she offers herself up to Morbin as a captive. Fortunately, Heather Longtreader discovers her plans and is able to take Emma's place when a bird comes to carry her away to the High Bleaks.
In the aftermath of the battle, the rabbits of Cloud Mountain begin a full-scale evacuation to Halfwind, Kingston, and possibly other locations. The Terralains, looking upon Picket's actions against Bleston as murder, attempt to apprehend him at Jupiter's Crossing but are repulsed. A three day truce is then arranged between Helmer and the Terralain officer Captain Vulm, but the two forces remain hostile afterwards. Word of the battle also precedes Helmer and Picket to Harbone Citadel, whose rabbits express their regret at being unable to offer any support. Emerson, an engineer at Harbone, is also able to create new glider capes for Helmer and Picket after hearing about the invention.