In 523 BC, the Persian pharaoh Cambyses dispatched an army across Egypt's western desert to destroy the oracle at Siwa. Legend has it that somewhere in the middle of the Great Dune Sea his army was overwhelmed by a sandstorm and lost forever. Two and a half millennia later, a mutilated corpse is washed up on the banks of the Nile at Luxor, an antiques dealer is savagely murdered in Cairo, and a British archaeologist is found dead at the ancient necropolis of Saqqara. The incidents appear unconnected, but Inspector Yusuf Khalifa of the Luxor police is not so sure...