In the town of Oceanside, Ruby Gillman and her family are secretly Krakens. Determined to fit in with humans, Ruby's mother Agatha forbids her from going near the ocean, including her school's prom at sea. Ruby's friends Margot, Trevin, and Bliss convince her to ask out her crush Connor anyway, but she accidentally knocks him into the water. Ruby jumps in and saves Connor — unknowingly triggering an underwater transformation — but new student Chelsea Van Der Zee takes the credit.