In this extraordinary adventure story, Billy Bartram, his father, and a secret society of philosophers and scientists venture into the American wilderness in search of the lost people of the Welsh Prince Madoc, seeking aid in the coming war against the French. Traveling in a flying airship, the members of the expedition find their lives frequently endangered in the untamed American West by terrifying creatures, a party of French soldiers hot on their trail, and the constant threat of traitors and spies. Billy will face hazards greater than he can ever imagine as, together with his father, he gets caught up in the fight for the biggest prize of all: America.