Krypto the Super-Dog (Johnson) and Superman (Krasinski) are inseparable best friends, sharing the same superpowers and fighting crime in Metropolis side by side. When Superman and the rest of the Justice League are kidnapped, Krypto must convince a rag-tag shelter pack--Ace the hound (Hart), PB the potbellied pig (Bayer), Merton the turtle (Lyonne) and Chip the squirrel (Luna)--to master their own newfound powers and help him rescue the Super Heroes.