Kabumpo in Oz (1922) is the sixteenth Oz book, and the second written by Ruth Plumly Thompson. It was the first Oz book fully credited to her. During Prince Pompadore of Pumperdink's eighteenth birthday celebration, his birthday cake explodes, revealing a magic scroll, a magic mirror, and a doorknob. The scroll warns the prince that if he doesn't wed a 'proper princess' within seven days, his enti...