I thoroughly enjoyed this book—not just because it involved time travel and Leonardo da Vinci—but because the two boys were so smart and resourceful and quick on their feet. I loved the notion that Leonardo was a time traveler (it actually explains a lot!) and none of the time travel elements in the book made me scoff or doubt the logistics like so many time travel books do. It was very well written with plenty of action, suspense, and espionage throughout. Highly recommended for grades 7-12.
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