When Earth intercepts a message from a long-extinct alien race, it seems like the solution humanity has been waiting for. The Undying's advanced technology has the potential to undo environmental damage and turn lives around, and their message leads to the planet Gaia, a treasure trove waiting to be explored.

For Jules Addison and his fellow scholars, the discovery of an ancient alien culture offers unprecedented opportunity for study...as long as scavengers like Amelia Radcliffe don't loot everything first. Despite their opposing reasons for smuggling themselves onto the alien planet's surface, they're both desperate to uncover the riches hidden in the Undying temples. Beset by rival scavenger gangs, Jules and Mia form a fragile alliance...but both are keeping secrets that make trust nearly impossible.

As they race to decode the ancient messages, Jules and Mia must navigate the traps and trials within the Undying temples and stay one step ahead of the scavvers on their heels. They came to Gaia certain that they had far more to fear from their fellow humans than the ancient beings whose mysteries they're trying to unravel. But the more they learn about the Undying, the more Jules and Mia start to feel like their presence in the temple is part of a grand design - one that could spell the end of the human race....