In 1989 someone is threatening to steal the crown jewels, so the Queen of England summons Mac B. to England to protect them--and when they are stolen from a locked dungeon cell, where Mac and Holcroft, one of the warders, are supposed to be guarding them, it is up to Mac to figure out how they were stolen, and whether the thief is the descendant of an Irish soldier-of-fortune who tried to steal them in 1671, or someone else entirely.

Mac B. is back . . . and this time, a new enemy is after the Crown Jewels! 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...

One day, Mac (smartest boy in his class in a small town in California) receives a telephone call from the Queen of England, recruiting him to find the crown jewels (well, actually just the Coronation Spoon) and so Mac embarks on his first adventure as a secret agent--with the assurance that the Queen will give him a note excusing him from school.

"This is a story of stolen violins. It's got mummies, museums, sandwiches, hostages, and a dangerous showdown with the Russian Red Army Choir. Open this book to find out more about my adventures. But beware--this mission is top secret and very dangerous!" -- cover.