When Benigno "Benny" Caldera is tasked with building a one-of-a-kind aquatic tank for Morgan’s Menagerie of Human Oddities at their upcoming Coney Island installation, he ends up roped into kidnapping its intended inhabitant: an ocean-eyed merman with copper hair, pewter skin, and a grudge against humanity. Compelled to care for the creature he helped cage, Benny joins the Menagerie, where its seasoned crew of curiosities adopts him as one of their own. But as his affection for the merman in the tank grows, Benny must reckon with the forces that have held him captive as well.