is the 12th volume in the series. Their dirigible/airplane, the Comet is still central to the boys' action and adventures, which this time includes a biplane-getaway bank robbery and a hundred-mile aircraft race. But, it's 1912, and heavier-than-air planes have improved significantly since the Wright brothers first flight in 1903. A synchronized machine-gun aircraft will emerge in 1915, and the first commercial flight will take place between the U.S. and Canada in 1919. While the Comet, a lighter-than-air craft still has the advantage of less fuel consumption over biplanes and triplanes, better engines will soon erase the difference and the boys will find themselves, "out-planed." But not this time.