Arlo Beauregard, a boy who is half-human and half-alligator, is placed in a sewage drain under New York City shortly after his birth, where he is taken by a stream of water into the ocean. Arriving in a swamp, Arlo is adopted and raised by a woman named Edmée. As a teenager, Arlo wishes to interact with other people but fears his alligator appearance will not be accepted by society. Edmée gives him his birth wristband on his fifteenth birthday and reveals to Arlo that he is from New York, and unaware that he was actually abandoned, Arlo decides to travel to the city to find his biological father, Ansel Beauregard.