Dear Beast Books in Order

Simon the cat resents his owner Andy's new dog, who lives with Andy's father. He sends Baxter a strongly worded letter demanding his departure, but their unexpected correspondence makes sharing the boy's affection a more complicated question.

When Andy's classroom pet disappears, an argument with his friend Noah leaves him miserable. Simon the cat and Baxter the dog exchange letters and compete to solve the mystery, each hoping to make their owner happy again.

Andy can enter only one pet in the annual parade, and Simon initially lets Baxter take the place. When the cat develops secret costume plans of his own, jealousy complicates the pets' efforts to please their owner.

When Andy's mother travels for work, Simon must stay with Andy's father and finally meet Baxter. The pets' expectations clash, and Simon's escape through a basement window leaves Baxter trying to bring him back before Andy notices.