It's 1939 and the woodland creatures of Gosport are enjoying their annual fete - but war will soon shatter their joy. Admiral Gizor, the evil grey squirrel that rules Portsmouth, invades Gosport with the aim of extermining the red squirrels and creating a pedigree society. Agatha Mumby, a feisty red squirrel, joins the resistance and seeks to keep an ancient holy relic out of the greedy paws of Gizor.