Arthur Makes Waves

Summary
The community pool is closed for repairs, so Arthur and D.W. accept an invitation to James' pool. Arthur ends up discovering that his old nemesis, Molly, is James's older sister.

Plot
Buster was describing Molly and Arthur's rivalry through ancient times, the Wild West days, and the days of your grandmother and grandfather, when suddenly, he got a message, hence the title card.

After the title card, when Arthur and D.W find out that the community pool is closed for repairs, they try to find other places to cool off. They try the Tibbles' pool, but it was loud and the pool popped. Next, they tried Muffy's pool, but Arthur's foot gets hit. Then they try the Senior Center's Pool, but it was full of ladies and the water was hot. Finally, they try the library since it has air conditioning until a kid coming out of the library tells them the air conditioner is broken.

They soon give up all hope, but then they go to The MacDonald's pool. That's when they discover James' sister is Molly. At first, Molly insults Arthur and makes one side of the pool for herself, and one side of the pool for James, D.W., and Arthur. Eventually, Molly befriends Arthur and D.W., but they can't get seen together or they will be mocked by their friends. They almost get busted on many occasions, but when Slink and Brain see them walking off together, it goes over the edge.

Buster, Francine, Muffy, and Brain (Arthur's best friends), and Binky, Rattles, and Slink (Molly's best friends) plan to do something about them and go to confront them at the MacDonald's pool, only to find Molly there. The friends think they may have stopped any sort of friendship from forming between Arthur and Molly, but are wrong as Arthur and D.W. hid away from plain sight before the group of friends arrived and Arthur and D.W. eventually head off towards the community pool.

Major

 * Molly MacDonald
 * Arthur Read
 * D.W. Read
 * James MacDonald

Minor

 * Francine Frensky
 * Buster Baxter
 * The Brain
 * Muffy Crosswire
 * Rattles
 * Binky Barnes
 * Slink
 * Thora Read
 * Timmy and Tommy Tibble
 * Patrick

Cameo

 * Mrs. MacDonald
 * Luke
 * 3rd Grade Male Rabbit
 * 3rd Grade Female Aardvark (Number 2)

Trivia

 * This is one of the episodes that focuses on water (with the others being The Shore Thing, Water and the Brain, D.W. All Wet, Swept Away, and Feeling Flush).
 * This is also the first episode with Molly and Arthur as friends.
 * This is the second episode D.W. calls Muffy by her name.

Episode connections

 * James made a reference to the episode "Kiss and Tell" where he asked D.W. if he wanted him to kiss her again.
 * Molly's hangout at the school playground in The Law of the Jungle Gym makes a brief appearance in a flashback.

Errors

 * In Slink's imagination, the red lightning bolt on his shirt disappears for a second before he drops his tray.
 * When Molly directs Arthur and D.W. on which side of the pool they're allowed to play in, her legs and lower torso are not visible in the clear water.

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