Sofia wants to care for all the animals in the world. But Mom does not think Sofia is ready for the responsibility of even one pet. Ready or not, when a hungry and sick-looking cat appears at the family's back doorstep, Sofia takes action. When Sofia is found feeding the cat, Mom gives in and agrees that a trip to the vet will tell them if the cat is healthy and not someone's lost pet. As the veterinarian introduces Sofia and readers to the important and wide-ranging work of animal doctors, Sofia learns how she might help all kinds of animals, including a little stray cat!