Po is gearing up to become the spiritual leader of his Valley of Peace, but also needs someone to take his place as Dragon Warrior. As such, he will train a new kung fu practitioner for the spot and will encounter a villain called the Chameleon who conjures villains from the past.

Ruby Gillman, a sweet and awkward high school student, discovers she's a direct descendant of the warrior kraken queens. The kraken are sworn to protect the oceans of the world against the vain, power-hungry mermaids. Destined to inherit the throne from her commanding grandmother, Ruby must use her newfound powers to protect those she loves most.