Fone Bone, Phoney Bone, and Smiley Bone are run out of their home, Boneville, and become separated in the wilds, but better fortune begins the three cousins reunite at a farmstead run by tough Gran'ma Ben and her spirited granddaughter, Thorn. But, little do the Bones know, there are dark forces conspiring against them and their adventures are only just beginning.

As war spreads through the valley, Gran'ma Ben, Lucius and Phoney Bone join the Veni-yan warriors at Old Man's Cave to make their final stand against the rat creature army.