The fourth book in the Marshmallow Pie the Cat Superstar series by Clara Vulliamy, the author-illustrator of Dotty Detective

After his success on the silver screen, Marshmallow Pie - a big, fluffy cat with an even bigger personality - has an exciting opportunity to act on stage in a grand theatre. It will be his first time in front of a live audience!
The bad news is, he has to share the stage with his unbearable neighbour and arch-enemy, Buster the dog. Pie is convinced Buster is out to ruin it for him! But there's a mystery to solve both on the stage and off, and Pie's refusal to trust Buster could have some unexpected consequences . . .
Told in the hilarious voice of Marshmallow Pie himself, his antics are illustrated throughout in black and white.