When a fragment of the Citadel of Bone is spotted, you can be sure the Hyperforce is after it. But when they come across an old legend piloting the team get a lot more than they bargained for. Sure enough, the Citadel is still in existence - and restoring itself. Will the monkey team be able retrieve this strange man's crew and to put an end to the evil before it starts? Or will this legend let his thirst for revenge end everything - including their lives?