Frost spends everything saving Cecil, a wounded merman, only to discover he’s using her to reclaim his first love, Vivian. Heartbroken, she saves the fearsome siren Locke with her last elixir. When Cecil’s obsession turns dangerous, Vivian helps her escape—just as Locke rises from a raging sea. Royal secrets, a hidden pregnancy, and an approaching tsunami threaten to destroy them all.
