Shoe Wars by Liz Pichon
Perfect condition
 
Step up to the challenge . . . win or shoes! Meet Ruby and Bear. Their dad has just invented the most amazing thing ever -- flying shoes! But his horrible boss Wendy Wedge knows that entering flying shoes will guarantee the Golden Shoe Award, and she will do anything to win the trophy. Ruby and Bear must outwit a bully, infiltrate a shady company, and rescue their dad all while keeping the shoes hidden. This can only mean one thing. It's . . . shoe wars!