The Penguin Always Rings Twice: A thief has been stealing the zoo's supply of peanuts, and all the clues point to Jeffy the elephant. But Martha and Skits are convinced of his innocence, and set out to prove it, with the help of a lemur, a bat, a penguin, and a baby tiger. The Martha Code: Martha has been eating letters again, but this time it's a secret code, and now no one can understand what she's saying. Then Martha becomes lost, and Helen can't find out where she is unless she can break the code in the phone messages that Martha is leaving.moreless