When Kal-El was sent to Earth from the dying planet Krypton, Superman's father initially sent his pet, a super-dog, as a sort of Laika test-pilot. Unfortuntely he gets into some sort of temporal anomaly and lands on Earth decades after Superman, where he is adopted by a boy named Kevin Whitney, who is aware of the superpowers of his pet. Krypto soon embarks on a crusade against the usual nasty things, assisted by other animal superhoeroes, including Streaky (the neighbour's cat) and Bathound (Batman's dog!)