The Mystic Rose chronicles the quest for the Holy Cup, the vessel used by Jesus during his last Passover feast with his disciples. Along with her father and her younger sister, Caitriona travels to the Holy Land to revisit the lands her father had been to so many years before on a holy pilgrimage. While in Constantinople, Cait witnesses the murder of her father by Renaud de Bracineaux, Grand Commander of the Knights Templar. Despite her father's last wishes, she vows to avenge his murder. With the helpful guidance of the White Priest, she steals a note from Bracineaux revealing his plan to remove the Blessed Cup in Aragon from the advancement of the infidel Moors. Cait seizes on this opportunity to squelch the Templars' selfish scheme and seeks to get the holy relic for herself. She stops in Damascus and pays the ransom for four Norse Knights -- for protection -- and continues on to Aragon, seeking her prize. But her travels bring unforeseen perils and obstacles at every turn.