Kaspar, Prince of Cats — Michael Morpurgo

Johnny didn't expect to end up with Kaspar, the Savoy cat, on his hands forever, and nor did he count on making friends with Lizziebeth, a spirited American heiress. Pretty soon, events are set in motion that will take Johnny - and Kaspar - all around the world, surviving theft, shipwreck and rooftop rescues along the way.