Ella Finn races against time to save the lives of her loved ones, finding herself pitted against two groups trying to manipulate her: The Institute want to use Elementals as weapons, while Destroy All Monsters are out to kill all Elementals. Caught between two opposing forces, Ella needs to escape and use the Book of All Life to open a portal into another world. Ella meets The Dreamers in this realm, immortal creatures with a secret link to all humans. She seeks their help to save her family and friends, but something evil lives within The Dreamers – something terrible enough to threaten Ella and all of humanity.

Former foes become allies as Ella and Elementals work together to stop dark powers from enslaving humans and controlling the world.