Unlike his three older brothers who have struck out on their own, Billy Bartram has always wanted to follow in his father's footsteps. John Bartram is a botanist with a world famous garden. Billy assists him by drawing the plants in the collection, but the boy longs to accompany his father on his frequent expeditions. It never occurs to Billy that his Quaker father might have interests beyond the natural sciences until one night a group of French spies break into John's office clearly searching for something specific.
Billy's courage during the incident does not go unnoticed by his father. When Benjamin Franklin visits to discuss the botanist's next trip, John suggests that Billy come along. Franklin, seeing Billy's artistic talent, agrees, and the young man is promptly initiated into the American Philosophical Society, a group of brilliant men who have put their talents at the service of the British colonies. Their next mission: to find the descendants of the Welsh Prince Madoc who are rumored to be living in the Ohio Valley. The Society hopes that members of this lost kingdom will support the British in the looming war with the French. Thus Billy sets out with a botanist, a mathematician, a chemist, an electrician, a philosopher and a mechanician in a magnificent flying ship to explore the New World.
Billy discovers more than just new plant life on this trip. The group watches herds of mastodons migrating and meets a legendary bear-wolf. When it becomes clear that the French are hot on their trail, John Bartram assumes that their Indian guide is a spy. Shocked that someone who is so adamantly opposed to slavery could be so prejudiced, Billy questions his father's judgment. With time Billy learns that there is much about his father's past he does not know and that he can still love and respect a man whose opinions differ from his own.
This action packed novel contains many surprises. Unlike most fantasy stories, Kirby incorporates just enough science in The Lost Kingdom to make it nearly believable. The complex lives of each of the characters in the story keep the reader guessing. Billy is a likeable protagonist who demonstrates daring and wisdom in spite of his mistakes. Jennifer Minicus is a mother and teacher currently living in Ridgewood, NJ.