When a brilliant young boy named Denny solves the most perplexing puzzle in the history of mankind, he and his caretaker sister, Jenna, are transported to the fantastic land of Gossamyr, where math is magic and the boy's unique condition gives him incredible power.
In the world of Gossamyr, power is as simple as comprehension. A spell is a theorem and the theorem must be written in the air and proven for it to take hold. Denny's unique gift allows him to solve theorems that would drive anyone else insane, but he doesn't think of the world on those terms. He can only solve problems, not consider the appropriate answer for a situation. Fortunately, the children are befriended by allies who strive to send the stranded siblings home before dark forces can use the boy's power for evil.