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.

A single father is deceived into a treacherous career as the grim reaper, while his precocious daughter Collette grows increasingly suspicious of his whereabouts.