Princess in Black and the Kitty Catastophe by Shannon Hale

The Princess in Black may know how to handle all kinds of monsters, but a kitten set on destruction? Me-OW! Duchess Wigtower had heard that pets are fun, but all her kitten has gotten her is nine lives' worth of problems. Eeeeek! It's time for someone else to deal with this catastrophe. Princess Magnolia is thrilled when a kitten lands on her doorstep, but just as she's about to play with Plumpkins (or should it be Hugmaster Floof?) the monster alarm goes off. When Princess Magnolia returns to her castle, her furry companion has carved up the wallpaper! In fact, each time Princess Magnolia leaves to help the Goat Avenger fight a very grouchy monster, her feline friend wreaks havoc. Has the Princess in Black finally met her match? Ten years after she first donned her cape, the Princess in Black returns for a purr fectly hilarious entry to the New York Times best-selling series.