Royal Revenge is a Nancy Drew and Hardy Boys Supermystery novel.

Nancy Drew becomes suspicious of Bess's new man, Cass Carroll, who has a deep, dark secret that is hidden with him, and only him. Cass is from Panaslava, a war-torn country with a bitter past. Meanwhile, the Hardys try to follow the trail of a gun for hire, and warn his target. The target's current location is at Little Panaslava, River Heights! The trio put the pieces together, and uncover the shocking truth.