I continue to enjoy this series, written entirely in letters and a newspaper article or two. In this particular title, the third one, Andy (with whom the two animals share custody) and his best friend Noah become estranged after the class pet, a leopard gecko, disappears, and Noah loses his turn at bringing Louie home for the weekend. Simon the cat is determined to get to the bottom of the mystery and make Andy happy again. Baxter the dog is completely on board with that idea, but Simon isn't interested in having help from Baxter. As in the other books in the series, the two correspond through letters to one another that capture their personalities and Baxter's inventive spelling. The competitive animals must rely on clues from Bubbles, Muffet, Guppies, and they get a great deal of help from Snail, who goes into spy mode and passes on his mail delivery responsibilities to Edgar Allan Crow. Once Simon realizes that geckos eat snails, he and Baxter become quite worried about his wellbeing. Of course, things are resolved in a satisfactory fashion in the end with the two pets continuing their correspondence, with Simon counting the number of misspelled words in Baxter's last letter. There's even a Doggy Dictionary translating Baxter's words. Colorful, kid-friendly illustrations complement the text, making this book so much fun to read, especially with its unique characters and distinct voices.