Rapture. Titan series, #1

Jamie Winters and Seth Cutter come from two very different worlds, but when their paths cross, everything changes. Jamie, a scientist who only believes in logic and data, must set aside her disbelief in mythical creatures to save one of Seth's people who has been captured by her boss. But when Jamie herself transforms into a mermaid, she begins to question everything she knows about the world. As they work together to save Seth's people from a deadly plague and stop a Sea Witch from ruling the oceans, Jamie and Seth must confront their prejudices and decide if their love is worth risking everything for.
With a stolen relic and a crazed scientist also threatening to unravel their world, the fate of an entire race rests in the hands of these two unlikely heroes. In this high-stakes, mythical world, will Jamie and Seth be able to overcome their differences and work together to save the undersea kingdom? Or will their prejudices and the chaos around them tear them apart? Rapture is a thrilling adventure that will keep you on the edge of your seat until the very end.