Grandpa awakes smiling. He looks out the window and hears a boarder, the reporter Bill Forrester, mowing the lawn. To Grandpa, this represents the first true day of summer. Downstairs at breakfast, Grandma tells him that Bill will soon put in a new lawn that never needs mowing. Dismayed, Grandpa hurries out and explains that he loves the sound of the mowers in summer and counts mowing the lawn as one of the small joys of life. Learning that Bill paid $15 for the flats of new sod, which is also designed to keep the dandelions away, Grandpa hands Bill 15 dollars and begs him to throw the flats into the ravine. Reluctantly, Bill complies. During his afternoon nap, Grandpa again awakes to the sound of the mower and realizes that Bill is doing it just so Grandpa can enjoy the sound.

Meanwhile, Leo, the town inventor, goes to his garage and begins work on the Happiness Machine. He struggles with the design and construction for 10 days, stopping only in the evenings to visit neighbors’ porch get-togethers, listen to the sounds of laughter, and note what causes the mirth so he can add it to the machine.