For Henry and his big dog Mudge, summer means going on a picnic in the park, taking a bath under the garden hose, and going to the top of the big green hill.

To relieve the boredom of a long, hot summer, Mr. Putter and his cat Tabby join their fun-loving neighbor, Mrs. Teaberry, and her mischievous dog Zeke on an adventurous sightseeing boat cruise.