When River, Freak, and Fiona discover a mysterious sofa sitting at their bus stop, their search for loose change produces a rare zucchini-colored crayon. Little do they know this peculiar treasure is about to launch them into the middle of a plot to conquer the world! The kids' only hope is to trap the plot's mastermind when he comes to steal the crayon. But how can three kids from the middle of nowhere stop an evil billionaire? With the help of an eccentric neighbor, an artificially intelligent domino, a DNA-analyzing tray, two hot air balloons, and a cat named Mucus, they just might be able to save the planet.