Entangled - Graham Hancock

As mankind faces its deadliest battle, two young women must unite to prevent the forces of evil destroying the world as we know it. But theirs is no ordinary alliance, for these two women live at opposite ends of history, until fate brings them together and their destinies are inextricably intertwined.

Leoni, a troubled teen from 21st Century Los Angeles, finds everything she's ever known thrown into disarray when a drug overdose catapults her into a parallel dimension.There she meets Ria, who is also suspended on the edge of time. Ria's world is violent and desolate in a way Leoni has never experienced - but only together can they stop the powerful demon Sulpa, the Eater of Souls.The embodiment of pure evil, Sulpa is preparing to perpetrate one final, horrific act of unspeakable wickedness, after which nothing will be able to stand in the way of his ultimate goal: the annihilation of mankind. Only Leoni and Ria can stop him...