Ontheirwaytoadulthood,thethreeoutsidersMark,MemoandBeckycomeintocontactwithafantasticworldcalledtheBlackTower.There,theGriffin,aworld-devouringmonster,hasbeenmercilesslyplunderingandsubjugatingalllivingcreaturesforcenturies.Andthethreefriends,ofallpeople,seemdestinedtoendthisreignofterror.