The secret inhabitants of a boarded up mansion on Manhattan's ritzy 5th Avenue include a philosophizing hobo and some GI families who are unable to find apartments during the post-World War II housing crunch.
The Garrisons, who raise dachshunds, are convinced by their vet to take in a Great Dane pup named Brutus, who thinks of himself as a dachshund, and whose identity confusion causes a series of humorous household crises.
All the earnest paleontologist wants is an intercostal clavicle to complete his brontosaurus skeleton. What he gets is an out-of-control toboggan ride with a scatterbrained heiress nuts about him (or maybe just nuts).