The Drowning Tide. The Atlantis Cycle, #3

They came as refugees. They became a legend. Atlantis was built by refugees from an even older civilization-the First Ones-who fled a cataclysm at the end of the last ice age. They settled on a chain of volcanic islands in the Atlantic, rich with a unique crystalline mineral called Orichalcum that could store and amplify energy. Over millennia, they learned to harness this mineral, developing technologies that seemed miraculous: clean energy, psychic amplification, weather control, even limited manipulation of time and memory.
But their greatest achievement was also their downfall-they learned to tap into the Earth's own energy grid, and in doing so, attracted the attention of something that had been sleeping beneath the crust.