▁the ▁series . ▁However , ▁in ▁May ▁ 2 0 0 8 ▁the ▁writers ▁announced ▁a ▁fourth ▁book : ▁Peter ▁and ▁the ▁S word ▁of ▁Mer cy . ▁ ▁Plot ▁summary ▁The ▁story ▁starts ▁at ▁Stone hen ge , ▁where ▁Lord ▁Om bra ▁was ▁seem ingly ▁destroyed ▁in ▁Peter ▁and ▁the ▁Sh adow ▁Th ieves . ▁ ▁Though ▁weak ened , ▁he ▁has ▁reg ener ated ▁his ▁conscious ness , ▁using ▁his ▁power ▁to ▁possess ▁others ▁to ▁gather ▁himself ▁together ▁so ▁that ▁he ▁can ▁return ▁to ▁Rund oon . ▁ ▁Meanwhile , ▁war riors ▁of ▁the ▁Sc orp ion ▁tribe ▁plan ▁to ▁in va de ▁M oll usk ▁Island . ▁W arn ed ▁by ▁Peter , ▁Fight ing ▁Pra wn ▁prepar es ▁for ▁war . ▁Event ually , ▁however , ▁he ▁is ▁forced ▁to ▁surrender ▁to ▁the ▁over wh el ming ▁force ▁of ▁the ▁inv aders ▁and ▁the ▁M oll us ks ▁are ▁ens la ved . ▁ ▁Mol ly ▁and ▁George ▁travel ▁to ▁Oxford , ▁where ▁they ▁discover ▁some ▁vital ▁information ▁about ▁Peter ' s ▁parents ▁which ▁suggests ▁Peter ▁himself ▁is ▁in ▁danger . ▁ ▁And ▁indeed ▁Lord ▁Om bra ▁and ▁his ▁fellow ▁shadow ▁cre atures ▁have ▁decided ▁that ▁capt uring ▁Peter ▁could ▁help ▁their ▁plans . ▁Lord ▁A ster ▁s ails ▁to ▁M oll usk ▁Island ▁to ▁warn ▁and ▁protect ▁Peter , ▁una ware ▁that ▁Mol ly ▁and ▁George ▁have ▁st owed ▁away ▁ab o ard ▁his ▁ship . ▁ ▁Peter , ▁wounded ▁by ▁the ▁Sc orp ions , ▁is ▁kid