Ignacio, a boy who attends the 5th grade at Steck Elementary School in Denver, approaches two of his classmates, Jack and Keegan with a problem -- his mom is missing. Ignacio tells the two boys that he had a vision and in the vision, Jack and Keegan found his mom. Jack is skeptical about the story, but Ignacio shows them a symbol and says that it is the first step in finding his mom. While they are looking for the symbol, Ignacio sees a picture of Jack's grandfather and says that he is in the vision too. They find Ignacio's symbol on the back door of a restaurant, but nothing seems to happen.
By an unusual set of coincidences, Jack's grandfather takes Jack and Keegan on a spring break vacation to a small town in Italy near the Adriatic Sea. With a plan to go to a sailing school, Jack passes through a time warp and finds himself in the year 1099 as a Squire to Sir James, a Knight of the Templar. The two leave Italy for the Levant, the Crusader States, to rescue the daughter of the Lord of Chartres who is in a castle in Edessa under siege by the Turks.
Jack sneaks into the castle to rescue the princess, but before he can get back to the coast, he and the princess are captured by the Turks and brought before the general in charge of the siege of the castle at Turbessel. The general releases them, but all the roads back to the coast are blocked by soldiers, Jack and the princess must travel through the Sultanate of Rum to get to Constantinople to find safe passage back to Italy. The princess has a treasure map that shows the location of a relic of the True Cross that she wants to bring to the new cathedral at Chartres.
They meet nuns in a monastery in Constantinople who help interpret the treasure map. The find the relic and their ride back to Italy. On the way across the Mediterranean Sea, they are shipwrecked and rescued by monks on the Isle of Crete.
When Jack reaches Italy, the Lord of Chartres asks Jack to train to be a knight in his army. Jack accepts the challenge.
Before Jack can get to Chartres, he passes back through the time warp and arrives back in the present time. Jack doesn't know if he had a vivid dream or a vision like Ignacio said he had. When he gets back to school he finds that Ignacio is no longer at his school, he moved over spring break.