As war spreads through the valley, the Bone cousins join Gran'ma Ben and Lucius at Old Man's Cave to make a stand against the rat creatures. But not everything goes as planned. By the end of the book, Phoney Bone is strapped to a stone altar and about to be sacrificed; Thorn is lying lifeless nearby; and the rumblings of an earthquake suggest that the Lord of the Locusts is about to be released. Fone and Smiley Bone must do something drastic to save their friends.