While Mrs. Castle works as an atomic scientist, Mr. Castle takes care of the house and children so efficiently that he soon finds himself with nothing to do until the backyard plum tree gives him an idea.
A fortuitous mistake brings happiness to nearsighted Mrs. Gimble who wishes her cat didn't eat so much, her cat Tom who dreams of roaming the wide world, and Mrs. Gimble's drifter brother who wants to keep his head warm.