What if you found a book that would let you travel through time, but you had to apprentice yourself to the school's librarian and meanest teacher to do so? That's the challenge faced by ordinary sixth-grader J.T. Middleton. When J.T. receives an undeserved week of after-school detentions, it sure doesn't turn out the way he imagines! Instead, he accidentally finds a mysterious blue book that transports him into the middle of a shootout in the Old West. Upon his return to the present time, he discovers the secret identities of his school librarian and the school's meanest teacher as the Protectors of Time. Now he has no choice but to return to the past as their apprentice. His job? To fight the evil destroyer of history known as "The Changer" who enjoys altering the past to make the future unrecognizable. J.T. travels back to the Wild West to save the life of a boy in the shootout at the O.K. Corral and to ensure the future of all humanity. This book contains J.T.'s first adventure as a time traveling apprentice.