In the epic conclusion to the Guardians trilogy, the team must travel to Ireland in search of the elusive Island of Glass. (Photo by Will Cockram, Flickr)

With the world in imminent danger, six gifted adventurers are on a legendary quest to find the key to saving the world and each other. But as they travel to Ireland on the last leg of their journey, will they find what they seek in time or will mankind soon find itself shrouded in darkness for eternity? Find out in Nora Roberts’ final installment of the Guardians trilogy, Island of Glass.