When Earth's seas aren't empty, where do alien refugees go? Jake Rose thought the hardest part was over. His alien mother's people found sanctuary in Earth's oceans, the dying planet Rison was saved, and he finally had a girlfriend who understood his half-human, half-alien existence. He was wrong. When Em Tullis vanishes without a trace, leaving only the cryptic word "Phoke," Jake's desperate search leads him to the storm-swept North Sea off Scotland. There, beneath the waves, he discovers Earth's most carefully guarded secret: the Mer-people-now called Phoke-have been hiding in the depths for centuries. And they're dying. A Risonian waterborne plague is spreading through the ocean, threatening not just the alien refugees but Earth's own native aquatic species. The Phoke emerge from their ancient hiding places, demanding a seat at the intergalactic negotiation table.

Suddenly, Rison's "simple" request to share Earth's empty seas becomes a three-way battle for survival. Worse, when Jake finally finds Em, she's infected with the alien organism that's killing the Phoke. Racing against time in the crushing depths of the North Sea, Jake must choose between saving his girlfriend and preventing an underwater war that could destroy three species. Because some secrets are buried beneath the waves for a reason. Perfect for readers who love: Middle grade science fiction with underwater adventure Alien contact stories with real consequences Scottish mythology meets space opera Action-packed chapter books for ages 9-14 Environmental themes and ocean conservation Romance that doesn't overshadow the adventure SIRENS continues the pulse-pounding Blue Planets World series, where middle grade adventure meets epic science fiction. Perfect for fans of complex world-building and heroes who fight for what's right.