"Simon the cat and Baxter the dog have finally learned how to share their owner, Andy. It helps that Simon lives with Andy's mom and Baxter lives with Andy's dad. When a problem comes up, they simply exchange letters to sort it out. Baxter's spelling has even improved . . . though not by much. But then Andy's class pet goes missing, which causes an argument with his friend Noah. Andy is so, so sad. Both Simon and Baxter want to solve the mystery and make Andy happy again. Which pet will collect the clues and piece together the solution?"--
