The fifth and final fantastical adventure in the 'Secret' series in which Cass, Max-Ernest and Yo-Yoji are accused of stealing a very-valuable-and-not-to-be-touched ancient Egyptian mummy from the local museum. They are determined to clear their names, but after getting accidentally trapped in a crate with a mummified cat, the three youngest members of the Terces society unwittingly find themselves on their way to the great pyramids of... Las Vegas. Amongst the dusty corridors of the Cairo Hotel and mysterious hieroglyphs of the Nile Nail Salon, Cass draws ever closer to uncovering the Secret...