Fans of this series, perfect for intermediate readers, will be delighted with this installment. Although her grandmother has put a moratorium on any more detective work and even cut free her hot air balloon, Ada Byron and her sidekick, Mary Wollstonecraft Godwin, end up doing what they do best--solving crimes or sorting out mysteries, after Ada receives a royal command to do so. She and her friends must figure out where an important possession of the future Queen of England, Victoria, known as Drina at her current age of nine, has gone. Ada and Mary don't even hesitate about going about their task, although Ada drives a hard bargain with her grandmother in order to get back into business. Although the author has taken liberties with the characters' ages, this is still an engaging series, and it's fun to imagine what things might have been like if Ada and Mary had been close in age. Back matter provides information about the time period and the actual characters encountered in the book. I have enjoyed all of the books in this series and appreciate the details in the narrative as well as the illustrations that appear throughout the story. Although I wasn't surprised at the mystery's resolution, I still enjoyed the journey, mostly because these girls seemed so lifelike. Young readers might have enjoyed the many word slips of Sir John, but I found myself wondering how any queen or educated person could have stood being around someone so self-assured and yet so ignorant of the proper words to use. YIKES!