Dr. Romero is a good doctor, but too fastidious to allow his children to have any pets but goldfish. That all changes during the winter of the terrible fever.
The weather is so cold, everyone in town is becoming ill with a mysterious fever. Even though Dr. Romero is know for his ability to cure any ailment, nothing he does can keep people from dying. Even his wife Catherine contracts the illness and dies. Dr. Romero misses his wife and becomes afraid for his children.
One night after everyone went to bed, Anna hears a sad noise and goes to investigate. She finds a little gray cat out in the snow and brings it inside to sleep with her. When she wakes up in the morning the cat is gone, and her father thinks it was all a dream.
Shortly thereafter, Anna wakes up with the terrible fever. Dr. Romero tries to keep her comfortable, but knows there is nothing he can do but wait. That night while everyone is sleeping, the gray cat comes back to Anna singing and carrying a red tray. Anna eats the tortilla the cat offers her, and in the morning she is completely cured.
The same thing happens to each of Anna’s four siblings, but each time the cat comes, the tray is a different color.
Dr. Romero is certain he is onto a medical breakthrough. He believes the cat is a delusion of a patient who is going to beat the fever.
Eventually, Dr. Romero gets the fever, too. Sure enough, the cat visits him, this time with the tortilla on a golden tray. He awakens in the middle of the night, cured and happy to be alive to care for his children. Then, Dr. Romero hears a noise at the door that sounds like crying. He goes to investigate, and finds five kittens on his front step.
Dr. Romero brings the kittens inside and puts one at the foot of each of his children’s beds. He names them after the words to the song the mysterious gray cat sang when they were all sick. Convinced now that the gray cat wasn’t a delusion, he sits down to write the story of the cat who saved them all with tortillas.
It is worth mentioning that the illustrations by Jeanette Winter are beautifully done in Spanish-American colors and motifs.