The story is about Dr. De Soto, a mouse dentist who lives in a world of anthropomorphic animals. He and his wife, who serves as his assistant, work together to treat patients with as little pain as possible. Dr. De Soto uses different chairs, depending on the size of the animal, or simply has the patient sit on the floor, using a stepladder or with Mrs. De Soto guiding her husband with a system of pulleys for treating extra-large animals. They refuse to treat any animal who likes to eat mice.