Luke, who lives in Iowa, finds himself in the middle of the flood season. Luke is a bit of a trouble maker and doesn't seem to have any problem breaking school rules with his best friend Tommy. Both fail to turn in a book report, which they were supposed to turn in by the end of the school year, claiming that the book they were supposed to read was, "The most boring book in the world." The principle makes them a deal, saying that if they can find that book on any of the "most boring book lists," that they would not have to do the report.
Luke does not find the book on any of the lists, but does find a book on one of the lists that intrigues him, because there is only one copy in the whole world, and it's whereabouts are unknown.
With the river rising, the library's book are endangered. Luke and Tommy offer to help transfer the book to higher ground. While moving the books, Luke sees the book he read about, called, "Leonardo's River," written by a man in the 18th century. However, he doesn't have time to read it, for so many other books need to be moved.
Later, the boys go back and steal the book, which does not seem to bother them at all.
They also discover that the book has been wanted by a man by the name of Erich Mueller, who knows that they have it.
After doing a great deal of spying, the boys learn that Erich Mueller has plans for a bomb in his briefcase, is German, and has kidnapped their teacher!
Luke finally reads Leonardo's River, which takes him forever because he keeps falling asleep, and discovers the secret to the book. In it, there is a brief mention of something that seems strange, a mention of being able to reverse time. After piecing clues together, Luke figures out that Leonardo Da Vinci must have made a time machine, but didn't want anyone to know about it. The author of the book had learned of it as well, so he hid the clues in the book.
The book disappears, and the boys are kidnapped by Mueller, who they learn is the child of a Nazi, and are taken to Germany. Tommy also magically happens to speak German.
The boys also figure out that Mueller wants to go back in time and give the plans of the bomb to Hitler to change history. Once arriving in Germany, the boys are astonished to see that Da Vinci already made the time machine, but no one knew how to use it. With the book, Mueller and his men use it to leave for the 1940s. Tommy and Luke follow, knowing that they have to get the plans back before they fall into Hitler's hands.
The boys manage to get the plans back and shred them into bits, but Mueller knows that Luke has an amazing photographic memory. Luke and Tommy race the men back to the time machine, with Luke and Tommy arriving first. They jump in and are transported back to present time, and then blow up the time machine as fast as possible.
The book has an intriguing ending, giving you the impression that the clues to the time machine were hidden in story.
I only sort of liked the book; however, I had some problems with the story. First, I didn't like that the boys didn't have any problem with stealing Leonardo's River. Second, I didn't like that Tommy happened to have every spy gadget under the sun, including night vision goggles and a lock-pick. Third, it seemed a little strange that Tommy was able to speak German (what are the chances of that?), and fourth, I did not like the beginning; the whole book didn't pick up until the very middle. Fifth, what boy has perfect memory? I just looked up photographic memory, and it is extremely rare.
So, over all, I had more problems with the book and I don't think I would recommend it just because these things bothered me. The idea was great, but a lot of things could have been changed. Like using a camera instead of having super hero memory. Or not being able to speak German at all. Or happening to find the book somewhere instead of stealing it.
