After years of being strictly house cats, Marco and Polo escape into the wonderful, but dangerous outside world and are sent on three challenging adventures by a group of cats known as the Club of Mysteries.
To prove themselves worthy of succeeding Texas Jake as leader of the feline Club of Mysteries, cat brothers Marco and Polo agree to bring him the comfrey that will heal his wounds.
Polo the cat finds his mother and tries to impress her with his courage as he and the other members of the Club of Mysteries set out on new adventures.