Cast into the ocean at birth by her human mother to spare her from superstitious fishermen, Marais is a mermaid with ancient sea-god blood: she commands sea creatures, and her tears form priceless pearls. Kind human boy Jasper rescues her, becoming her loyal "brother" and their cross-species bond becomes her anchor.
Her rare powers draw greedy hunters, a cold scientist, and ruthless tycoon Mr. Delacroix, who launches "Project Leviathan" to seize her immortality-bestowing blood. Marais evolves from a fragile outcast into a towering ocean guardian — saving her mother from ritual sacrifice, freeing captured mermaid kin, and defending all she loves.
She rises as Queen of the Sea, watching over both her underwater clan and her beloved human family on shore.
