Mimi, Papa, Christina, and Grant really get in over "skulls" in this mystery set in the Yucatan Peninsula. When they go to explore ancient Maya ruins, "number" clues seem to abound! But what is someone trying to lead them to... or away from? Snakes... human hearts... a wall of skulls... human sacrifice? "How creepy can you get?" the kids wonder. But in searching for clues, they encounter the wonder that is Mexico and find themselves laughing at things they never thought could be funny along the way!

Like all of Carole Marsh's Mysteries, this mystery will also incorporate history, geography, culture, and cliffhanger chapters that will keep kids begging for more! This mystery will include SAT words, educational facts, fun and humor, a built-in book club, and activities.