The Lewis family, Maggie, Sam, and their two pre-teen daughters Laura and Abby, goes on a vacation to a coral reef archipelago off the Yucatan peninsula. Hiking, they enter a Mayan temple and encounter an evil, extraterrestrial creature in the form of an immense scorpion. The creature was accidentally formed when an advanced civilization learned how to isolate and set aside the dark emotions that haunted its members. The creature scatters each Lewis to a different place and time on Earth, and each makes her way back to reunite and confront the creature. Each is stalked in her journey by an offspring of the scorpion and each is assisted by an ally whose past is intertwined with the creature. At the end, they battle the scorpion and her hoard in the valley reached through the temple where she has lived for eons.