The story takes place in the 1950's, you can tell by the fashion of his clothes and the interior of the house. Stephen is a seven-year-old boy who has run away from home. He is a rough-and-tumble boy, you can tell by the holes in his pants, and his messy hair.
He ran away to grandma's house, because his mom doesn't have time to make cookies. At grandma's he found the cookie jar and a large glass of milk, and now he's hiding in the closet eating all the chocolate chip cookies. And Stephen is in heaven!
His grandma's well-behaved dog, Buddy is waiting patiently for Stephen to share his cookies. And when Stephen finally shares, Buddy becomes the happiest dog in the world. He was well rewarded for waiting.
As Stephen is enjoying his stolen cookies, his grandpa, who Stephen calls poppa opens the closet where Stephen is hiding. Poppa is amused as Stephen offers a cookie and takes the jar away. After all, Stephen shouldn't be stealing cookies.
Grandpa tells grandma, and she promptly give the cookies back to Stephen, telling him that he can come over anytime!