Marlin lives a resourceful life on the edge of a bustling port town, relying on his wits and the loyal companionship of Marlimon—a magical, purple-furred monster who can only be seen by Marlin. Together, they scavenge the market, share secret games, and fend off loneliness. But when Marlin's world is turned upside down, he is forced to leave his hidden treehouse and, with his few remaining magical clamshells, embarks on a journey to reconnect with Marlimon and find his true family. Along the way, he discovers a mysterious girl, Coral, who also has a magical monster and shares Marlin's silver-eyed, sea-born heritage. Guided by clues, the two uncover their underwater roots and face a choice between their land-bound life and a mystical world of belonging below the waves. The Good Monsters is a captivating tale of courage, friendship, and discovering home in the most unexpected places.