Three best friends — Y/N, Mara, and Theo — win a VIP after-hours aquarium tour that turns out to be a trap: they're surgically and permanently transformed into mermaids to become the aquarium's new "living exhibit," their legs fused, gills cut into their ribs, no way back and no rescue coming. Trapped together in a tank disguised as a rescue exhibit, each friend handles the horror differently — Y/N clings to hope and memory, Mara goes eerily silent and withdrawn after the worst transformation of the three, and Theo, after a botched "correction" leaves his arm reshaped into a fin, slowly and disturbingly starts to adjust to captivity. The real horror isn't the transformation itself, but watching each other change — and wondering if the people they love are still in there at all.