The Crown Jewels are in danger... again! When the jewels go missing from inside a locked room, Mac's spy skills are put to the test. How did the thief break in? Where did the jewels go? And will Mac be able to solve this locked room mystery before the thief escapes? This mystery isn't just a whodunit... it's a howdunit!

The action in this new adventure is nonstop, as Mac travels to an ancient Irish castle to solve the mystery. There, he encounters everything from killer king cobras to bizarre ice sculptures... and even a revenge plot dating back hundreds of years! Will you be able to solve the mystery before Mac does? Also features historical facts masterfully woven throughout the plot, and full-color illustrations on every page. Don't miss the newest installment of this totally smart and sidesplittingly funny new series, Mac B., Kid Spy.

Mac Barnett is the author of several books for children, including Extra Yarn, illustrated by Jon Klassen, a Caldecott Honor Book and winner of a Boston Globe-Horn Book Award, The Wolf, the Duck, and the Mouse, a New York Times bestseller, and Sam and Dave Dig a Hole, a Caldecott Honor Book and winner of the E. B. White Read Aloud Award. He is the co-author, with Jory John, of the New York Times best-selling series The Terrible Two. Mac Barnett lives in California.



Mike Lowery, creator of the Doodle Adventures® series and The Kid’s Awesome Activity Calendar, is an illustrator whose work appears in everything from greeting cards to children’s books. He lives with his wife and daughter in Atlanta, Georgia.

Chapter One: Spy MasterChapter Two: The Great Game Chapter Three: Spy Life Chapter Four: The Queen’s PalaceChapter Five: The Corgi Room Chapter Six: Bad BloodChapter Seven: Young Blood Chapter Eight: A Locked Room Chapter Nine: Slumber Party Chapter Ten: First WatchChapter Eleven: An Important Lesson Chapter Twelve: Robbery! Robbery!Chapter Thirteen: Impossible Crime Chapter Fourteen: Hot Pursuit Chapter Fifteen: Ahhhh!Chapter Sixteen: Ahhhhhhh!Chapter Seventeen: Ahhhhhhhhhhh! Chapter Eighteen: Jokes and RiddlesChapter Nineteen: Plink! Chapter Twenty: Misdirection Chapter Twenty-One: Mac Cracks It!Chapter Twenty-Two: Whodunit Chapter Twenty-Three: AxedChapter Twenty-Four: Wrapping and Bows