Ages 9 to 12 years. Keith and his father enjoy building model airplanes, but when they do not follow the instructions, their model crashes. As Keith is exploring an old pawnshop for a new plane to fly, he uncovers a model biplane that bears strange, experimental modifications -- and that comes with a warning from the shopkeeper. The changes made to this model remind Keith of the contraptions a maverick boyhood friend of his used to create. With the caveats of the pawnbroker still in his mind, Keith is surprised to run into his old friend again, this time for a surprising adventure with the odd model biplane. In their adventures, they discover that events are capable of not only changing the people involved but also altering the very objects around them.