Inspired by the real-life exploits of the author's grandfather, who was a sailor, balloonist, and aviator at the turn of the 20th century, King of the Air and Sea is an exciting, fun-filled tale of two teenagers, Oliver and Jack, who in their adventures together solve mysteries, learn that life is not all fun and games, and discover that part of growing up is taking responsibility for your own actions. At age fourteen, Oliver stows away on the Golden Lady, an old sailing ship set to round Cape Horn. Discovered, he must prove himself a worthy seaman. On the ship, Oliver meets Jack, the captain's daughter, who's happiest disguised as a common sailor, and the two become best friends.

When the Golden Lady arrives in New York, Oliver must fend for himself. He answers an ad for a circus performer at the Coney Island Amusement Parks, where the eccentric Professor Le Strange hires him as a balloonist. Jack runs away from a girls' boarding school and makes her own way to New York, where the professor hires her as a lady aeronaut. Eventually, the reunited adventurers pool their earnings, buy an old biplane, and with their pets, Frisco the dog and Achoo the parrot, enter the Transcontinental Air Race sponsored by newspaper magnate William Randolph Hearst, who promises a $50,000 prize to the first aviator to fly coast to coast.