Eleven-year-old math prodigy Ada Lovelace, daughter of the famous and infamous poet Lord Byron, is a genius. Isolated, awkward and socially inept—but a genius. Mary Godwin, age 14, daughter of radical philosopher William Godwin and feminist writer Mary Wollstonecraft, is a romantic. It has been arranged for Mary and Ada to be tutored by the young man who calls himself Percy B. Snagsby, a nervous fellow who may or may not be a spy. Every day, Mary rides to the Byron estate in a carriage accompanied by Charles, a stowaway boy she is supposed to pretend isn't really there and who all the while keeps his nose in a book.

As the two girls become fast friends, their irrepressible curiosity leads to the formation of the secretive Wollstonecraft Detective Agency. Their first case involves a stolen pendant, a false confession, and an array of fishy suspects—but these are no match for the deductive powers and bold hearts of Ada and Mary.

Playful historical references and witticisms abound in this comic romp featuring Newgate Prison, a renegade hot-air balloon ride across the rooftops of London, and word-play worthy of the literary characters who inhabit the story. The Case of the Missing Moonstone is funny and fanciful middle-grade fiction that is guaranteed to delight readers of all ages.