The Lost Souls. Timethreader Series, #5

The Intergalactic Council calls it the Devourer. The Order of Orphic Vitae thinks it is the path to eternal life. Arthur Templar calls it the worst thing he has ever felt - vast, hungry, and waking up beneath the earth. Arthur is eighteen now, and the stakes are no longer local. The ancient network that runs beneath Elderberry Valley extends across every continent on Earth, possibly across other worlds.
Something has been imprisoned inside it for ten thousand years - not a creature exactly, but something that thinks, that wants, and that has spent millennia absorbing the awareness of mllions of souls. Seraphina Volker believes she can release this entity and negotiate with it for transcendence and ternal life. She has been systematically activating nodes across the globe, turning a preservation network into a weapon.
But Volker isn't the only one racing toward the network. Dr Elena Corvus - brilliant, pragmatic, and playing a longer game than anyone realises - has her own plans for what happens after. Arthur and his five cousins are deployed across Antarctica, the Mariana Trench, and the ancient Core chamber beneath what used to be Thunder Mountain. The seals that have held for three thousand years are failing.
When everything breaks at once, Arthur discovers that the Devourer cannot be destroyed, it is essentially immortal. It requires something neither strategy nor force can provide. The Lost Souls is the fifth and final book in the Arthur Templar Timethreader Chronicles - a series set in the fictional Elderberry Valley of Western Australia, where ancient cosmic forces intersect with the lives of six psychically gifted teenagers who carry Pleiadian heritage they are only beginning to understand.
The series begins with The Curse of the Nibiru, when Arthur and his friends are twelve and their valley is threatened by a Nibiruan mining operation. By Book Five they are seventeen and eighteen, facing a crisis that threatens every conscious being on Earth - and the ancient network that connects them all is finally ready to become what it was always meant to be. For readers who loved Percy Jackson's mythological depth, Ender's Game's moral weight, and The Darkest Minds' fierce ensemble, this series offers something genuinely different: a fantasy grounded in Australian landscape, Pleiadian mythology, and the idea that the most powerful thing a person can do is choose connection over isolation.