Sgt. Chesterbarrel is the rough and ready leader of a squad of soldiers in the Machovian army. General Lunace orders them to attack a stronghold run by Lord Gaylord that is said to have a doomsday weapon capable of destroying the Machovian empire, or that of their enemy, the Goyimians.
Chesterbarrel's squad includes Moonshadow, Ira, Horntoad, and Rigarollo, all of them unwilling recruits. They land on the planet Bingbangboom to attack Gaylord's headquarters. Chesterbarrel, Ira, and Moonshadow don special bird-shaped flight suits and infiltrate the castle. However, when they get in, they are welcomed with open arms by Gaylord, who as it turns out is not actually a threat. Instead, he is using his pretend weapon to cow the two empires into submission, and thus create peace. Gaylor's castle is in fact a refuge for all those who want to join his movement for peace.
The gruff Chesterbarrel, tired of war, unexpectedly but happily joins Gaylord and gives up his life in the army, but Moonshadow and Ira, who see Gaylord's castle as another Zoo, move on.