Hafsa, a talented art restorer newly hired at the Louvre, comes face to face with a millennia-old Mesopotamian mask representing the storm god Baal Phegor, known to the uninitiated as Belphegor. Soon entangled in a series of inexplicable disappearances, with no memory of her involvement, she finds herself in a race against time at the heart of the world's greatest museum. Hafsa must fight both her pursuers and her own demons to uncover the truth and understand the powerful bond that ties her to Belphegor.