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.
While trying out the spy glasses, spy hat, and other items in their new spy kit, seven-year-old Henry and his dog Mudge make a new friend and form a spy club.
Henry and his dog Mudge are invited to a sleepover in Patrick's attic, where they watch monster movies, eat pizza, and enjoy a contest to determine whose dog is the best popcorn catcher.