Freelance pilot and treasure hunter Helen Highwater finds herself in too deep when she agrees to retrieve an ancient mask from a long-forgotten temple. Suddenly her employers are trying to kill her and silence her forever. She enlists the aid of Abigail Dawson, a prim English historian and archaeologist whose dreams of fieldwork have run aground in the backrooms of an old museum. Together they must race against time and Helen's pursuers to decode the mystery of the mask and discover a terrifying secret that has lain dormant for centuries.