Sir Kieran Hage had a mission to fulfill. As the head of a peace delegation intending to end the Siege of Acre in 1192 A.D., he carries the crown of thorns said to be worn by Jesus Christ as an offering of truce from the Muslim warlords. It is a holy relic of the most important magnitude. Unwilling to accept peace, however, Kieran's men turn against him and make an attempt on his life. Wounded, Kieran seeks out a man who he believes is a physic. He is greatly mistaken. Not a physic but an alchemist, the mysterious man does the only thing he knows to do for the dying knight - he puts him in to an eternal sleep so he will not bleed to death, suspending his bodily functions, only to be awakened by the power of truly deep emotion. Eight hundred years later, Dr. Rory Osgrove excavates the English knight from his dusty tomb and an accidental kiss brings him back to life. Together, they shared an adventure in Modern Times before a twist of fate sends them back to his time.

Back in his element, Kieran is determined to finish his mission of peace. He must return the crown of thorns to England. But the same assassins who tried to kill him the first time are after him again, patterns of life repeating themselves, and Kieran, now with Rory, finds himself back on the run. Over dry land and heavy seas, he and Rory flee the assassins, struggling to make their way back to England. But as they travel, the real Medieval world opens up. To Kieran, it is the world he knows but to Rory, it is much different. The modern girl finds herself in a land of no cell phones, bathrooms, antibiotics, or airplanes. She must learn to live in this strange, new world, a place she thought she knew a great deal about until she actually found herself in the midst of it. Dangers lurk everywhere as she struggles to adjust, but even as she tries to acclimate to an environment that is much more different than she ever imagined, bigger fears come to light.