When Elena Santiago's father, an archaeologist, brings her and her friends to an ancient site in South America, they uncover a structure hidden deep within an Aztec city. But this is no ordinary gateway-it allows them to travel into fantastical realms. A malevolent figure, trapped within the realms, is hunting them. As the barriers between realms begin to collapse, Elena and her friends must decipher the secrets of the ancients, confront their darkest fears, and find a way to stop the being before it's too late.