D.W. develops a fear of octopuses while on a field trip to the aquarium with her class. The next day, the Reads go to the beach, but D.W. refuses to swim because she thinks there are octopuses in the water. However, after Arthur and his friends get in trouble for playing a prank on D.W., she overcomes her fear. Buster and Arthur discover a fossilized dinosaur footprint on a class trip to a state park. Buster takes it home, which is against the park rules, but later feels guilty and decides to give it to the park.