Book 3 in the interlinked Zac Power Extreme Mission Super Series! Zac's whole family has been recruited to sneak into the City of Snow. They have to save the third piece of IRIS - but it's hidden in the crown of the king himself! And when Zac's family is taken hostage, he's faced with the toughest decision of his spy career. Will he stay and fight for his family, or go and save the world from BIG and IRIS?