Eight-year-old Lyon and his best friend, a cat named Max, want to have fun in the underground passageways connecting the Cat Kingdom and Dog Kingdom. But they are drawn into an interspecies conflict over a pond with magical powers.

Espy, a spy for the Dog Kingdom, wants to steal the key to the magic pond from Lyon and Max to give to her king, His Royal Pawness. Lyon and Max have to resort to their best tricks to stop Espy. An unlikely ally comes to their aid, but not before Lyon gets in big trouble with his parents.