The right cause can topple a kingdom . . . Once upon a time, the kingdoms of Wales were rife with magic and conflict - and Mer is well-acquainted with both. For years, she has been running from the prince who bound her into his service - and forced her to kill thousands with her water magic. Now, all Mer truly wants is a quiet life, far from power and politics. But then Mer's old handler offers her a proposal: use her powers to bring down the very prince that abused them both. With the help of a fae-cursed man, a snarky thief, and a corgi that may or may not be a spy, Mer must decide if she's prepared to run for the rest of her life, or to stand and fight for her freedom - and peace . . .