George goes to the annual weekend fair with Allie and The Man with the Yellow Hat. Allie plans to win a teddy bear from a game. When she learns she is poor at the game, George convinces her to practice at home.

George and Allie wash The Man's guitar, but it breaks down, so they build a new one made out of other stuff. It doesn't sound well, but it still is used in a concert. This guitar gave The Man an idea for lyrics for his song.

George and the Man with the Yellow Hat visit the Clown College for Pepe El Loco's Big Show. George has to substitute for a messenger clown and has to make pickups. He does not know how to count from any number except one, so every time he makes a delivery, he must start on floor one and count his way up the building.

Professor Wiseman is set to launch B.I.R.D., her bird migration tracking device, but the remote control isn't functioning properly, as everything on it is reversed.

George and Allie are determined to help Howie the Hog win a blue ribbon at the state fair.

George is thrilled to visit Pizza and Einstein's Space Center to help solve a problem with the Mars rover. But a sleepy monkey falls asleep and wakes to discover that he and the Man with the Yellow Hat are going to Mars.

When the grocer runs out of masa (cornmeal), George and Marco are worried they won't be able to make Marco's famous tortillas for his abuela's birthday. Thankfully, Uncle Enrique makes it his mission to find the key ingredient. During their ride on the "Tortilla Express," all three learn where masa comes from and how it gets from the farm to Marco's table.

It's Lake Wannasink Lake's 100th anniversary and George is in charge of the main attraction - the town's 100-year-old-flag with 10 stripes and 100 stars. When the stripes accidentally blow away, George runs around the countryside to retrieve them.

Fearless George" and his comrades (aka Steve and Betsy) are playing a make-believe adventure with George's toys. But putting away toys only to set them up again the next day really eats into play time.

When Hundley notices a big dog named Goliath helping the Doorman in the lobby, he wishes he were taller. George and Marco try to help the dachshund by giving him stilts, platform shoes, and even a fun house mirror to makes Hundley look big. But nothing cheers Hundley up until he figures out that good things come in all sizes.

On the first hot day of summer, George, Bill and Allie decide to take a dip in Bill's pool only to discover that the pool is filled with algae! Even oars, rubber boots, pots, pans, and yellow rain hats won't empty the green water. Hot and tired, George gets a refreshing idea while sipping lemonade from his super long straw. Simple siphon to the rescue.