It's not easy protecting a city from ocean monsters, but that's the job of Harbor Warden Casella Havard. Of course, nobody knows she's actually part monster herself.

Being half-mermaid comes with plenty of complications, a talking sea otter for a best friend, an on-again/off-again romance with a cute veterinarian, and maneating krabbor that are increasingly coming ashore to abduct tourists.

Just as the casework is piling up, an angry city official barges in and blackmails Casella into taking a missing persons case.

Portland has always been home to strange things, but there's a mystery lurking in the depths that only its Harbor Warden can solve. Of course, with a (maybe?) girlfriend and a talking otter in her corner, Casella feels practically unstoppable.