A whole year has passed. It's October again... or is it? As California teen, Arizona Darley, contemplates traveling back through the portal to seek out her dad, her life is plunged into a whirlwind ride through the unknown. But this time, she doesn't disappear through the portal. Has Arizona been kidnapped-again? Is Raj Sen to blame? Could Dillard have taken her? As Kellan, David and her parents launch a frantic search with the help of the Wanderers, it becomes apparent that things are much more complex than they seem - for all of them. While investigating her daughter's latest disappearance, Olivia faces shocking revelations about the Wanderers and her life with Rupert. In the meantime, what's happening in New Jersey? Are both of Arizona's worlds about to collide? Quantum is the third book in the Portal Chronicles. Catch the start of Arizona's adventures in Portal and Equilibrium.