The Crown Jewels are in terrible danger once again, and Mac B is the only kid spy who can save them. When the world's most valuable jewels vanish completely from inside a heavily guarded, locked room, Mac is called in to solve an impossible mystery. How did the sneaky thief break in? Where did the shiny jewels go? And most importantly, can Mac solve this puzzle before the criminal escapes forever? Your mission takes you straight to an ancient, creepy Irish castle where the action never stops. Along the way, you will face killer king cobras, bizarre ice sculptures, and a revenge plot that dates back hundreds of years. You will even learn real historical facts while trying to crack the case. Put on your detective hat and see if you can figure out how the thief pulled off this locked-room crime before Mac does.