In 1684 France, Louis XIV (Pierce Brosnan) - the Sun King - is the most powerful and influential monarch on the planet. But his birthday is approaching along with a rare solar eclipse and he’s worried about the future of France. His spiritual advisor, Père La Chaise (William Hurt), comforts him, while his physician, Dr. Labarthe (Pablo Schreiber) informs him that scientists believe mermaids contain a life force which grants immortality. Louis XIV’s quest for immortality leads him to capture a mermaid’s life force, but his immovable will is challenged when his long-hidden illegitimate daughter forms a bond with the magical creature.