The events that led to the Wyvern Massacre were set in motion by Demona and the Captain of the Guard. Both were angered by the disdain with which Princess Katharine and her people treated the gargoyles who defended them nightly. They plotted to lure Goliath and the rest of the gargoyles away from Castle Wyvern at night, making sure they could not return to the castle before sunrise. The Captain would sabotage the humans' defenses, allowing the Vikings to easily take the castle that night. The people of Wyvern would be taken captive and the gargoyles would be free to resume life as they had known it before their alliance with humans.
The plan went awry almost from the start. Goliath did not wish to leave the castle unprotected and although both Demona and Othello offered to accompany him, he pursued the Vikings (actually only a few soldiers leading horses as a decoy) with only Hudson. Since nearly the entire clan would still be present at Wyvern Hill that night, Demona reluctantly agreed with the Captain to modify the plan. The Captain signalled Hakon, the Viking leader, to attack the following day while the gargoyles slept and he vowed to Demona that he would guarantee the gargoyles' safety. Fearing what the other gargoyles would think if they knew of her treachery, Demona did not warn any of her clan of the coming attack, instead leaving the job of protecting them to the Captain. She did, however, flee the castle shortly before dawn, abandoning her clan to their fate. The Captain tried to defend the sleeping gargoyles that day, but Hakon did not trust his claims that the clan would not pursue his troops once the humans were gone. Hakon and his men shattered the gargoyles in their stone sleep, all but destroying the entire clan.
A total of seven gargoyles survived the Wyvern Massacre. Goliath and Hudson discovered that the Vikings had created a diversion to draw them away from the castle, but were unable to get back before sunrise. The Trio and Bronx had been sent to the rookery earlier by Goliath as punishment for an argument with some of the humans. Demona survived from her hiding place, but did not reveal herself to the other survivors out of guilt for causing the massacre. By the time she returned, planning to say she had gone looking for Goliath and had been away from the castle at sunrise, Goliath and the others had all been placed under the sleep spell by the Magus. The thirty-six eggs in the rookery also survived and would form the basis of the Avalon Clan. ("Awakening" Part One, "City of Stone" Part One, "Reawakening")