Book 5 in the Area 51 series Scientist Lisa Duncan has found the legendary Holy Grail. But can she keep it out of enemy hands? That enemy is the Airlia, frighteningly sophisticated extraterrestrials who came to Earth millennia ago and left behind ancient riddles in the form of the Great Wall of China, the Egyptian pyramids, and the statues of Easter Island. Now the aliens have returned to take over the planet. A team of Area 51 soldiers and scientists race to find the Airlia's keys to power-including the Grail-before the aliens do. But with Lisa surrounded by the Airlia at the Great Sphinx of Giza, her lover, Special Forces officer Mike Turcotte, must launch a daring rescue...and make an impossible decision: save the girl or the Grail?