The Simpsons and the Van Houtens are enjoying a picnic in the park. Marge spots a bee on Maggie and as Homer tries to shoo it away, gets his head caught in a beehive, falls into a blueberry patch and wraps himself up in the (green) tablecloth. When all is said and done, he resembles Marge, who tells him not to mock her at picnics. Milhouse's dad makes an announcement (and it's not that he and Luann are brother and sister, as Bart was hoping for). He and Luann are getting remarried. Milhouse is happy that they're a family again.
Homer's having problems choosing a tie for the ceremony. He can't seem to decide between a bolo, clip on, or piano keys. Marge says he should wear a tie that matches the color of her eyes. When Homer is unsure of that color ("Is beautiful a color?"), Marge gets upset and won't let him see her eyes until he remembers.
Kirk and Luann decided to remarry at a "not safe for swimming" beach. At the ceremony, Marge is wearing sunglasses. Reverend Lovejoy begins the service and is interrupted by a volleyball game. The Van Houtens are once again man and wife and Kirk and Luann head off on their second honeymoon cruise, leaving Milhouse to stay with the Simpsons. Homer tells the boys a bedtime story, which ends with "...and that's why you'll never see a shark with monkey arms." Meanwhile, on the cruise, Kirk decides to (this time) carry Luann over the threshold. Bad idea. He's unsteady on his feet and the two end up falling overboard.
Bart and Milhouse are outside playing and find an animal hole. Bart puts a hose down into it to find out what creatures reside there. It's spiders, who ruin Lisa's tea party. Milhouse says he's having so much fun that he doesn't care if his parents ever come back. The boys' fun is interrupted by the arrival of 2 representatives from the cruise line who inform Milhouse that his parents are lost at sea. Milhouse feels their disappearance is all his fault. The cruise line guys say they'll try to find his parents, but the sea's really big. The Simpsons tell Milhouse he can stay with them as long as he needs to. Homer tells him he can even stay up an hour later, so he can have more time alone with his thoughts.
The next morning, Milhouse comes down for breakfast and is barraged with Homer's product placement attempts - all ocean and/or sea-related (Ocean Spray, Cap'n Crunch, Seven Seas dressing, Chicken of the Sea). Marge tells him to cut it out and sends him to Moe's, where he can "drown his sorrows with Anchor Steam beer." Marge tries to get Milhouse "snazzed up" and tells him not to give up hope. Just then, the cruise rep pops up and says they've given up the search for his parents. Bart tries to cheer Milhouse up by letting him kill him in video games, but Milhouse is too miserable. Maggie offers Milhouse her bottle and he drinks from it. He checks his reflection and realizes he's become the "world's biggest baby," so he takes off the nipple and chugs down more milk--he needs to be a man. Homer is still trying to figure out what color Marge's eyes are. He finds their wedding album, but it's got a combination lock on it. Homer asks Marge what the combination is and she replies that it's their anniversary which, of course, Homer doesn't remember.
Nelson and the boys are playing marbles on the playground, when a marble leaves the ring and lands by a mysterious stranger, Milhouse. Lisa is surprised to see the new Milhouse and Bart tells everyone to be super nice to him. Nelson says "Your mom called, she said 'Glub, glub, glub.'" Milhouse doesn't cry, as he says he has no tears left. Lisa seems attracted to him. He tells Nelson to beat him up so that maybe he'd "feel something" but Nelson doesn't go through with it. Nelson tells Bart that he's no longer the coolest kid in school. Bart disagrees. At lunch, everyone's sitting with Milhouse. Bart can't even get Ralph to sit with him. The bus drops everyone off and Milhouse is scoring digits and even gets an invite to hang out with Nelson. He just wants to walk alone and work stuff out. Bart tries to impress the gang by putting his backpack on his front and krumping, but it's not working. Marge volunteers to krump with Bart--she's quite the krumper.
Bart wants Milhouse to be happy again, so he can regain his cool factor. He figures if Milhouse had family to take care of him, he'd be happy again. He remembers that every Christmas, Milhouse got butter cookies from an uncle in California, so he calls directory assistance in Solvang, "a little bit of Denmark on the California Coast" and tracks down Milhouse's uncle. The uncle flies in on Solvang Air and Bart waits for him with a sign, expecting a dweeb (the guy's name is Norbert, for heaven's sake.) Uncle Norbert actually flies in on a biplane, and he looks like Indiana Jones (call him Zack). Bart brings Uncle Zack to Milhouse and he says he doesn't need him; he can take care of himself. Milhouse gives his uncle a hug, which only endears him more to his schoolmates. Homer is raking leaves and still trying to recall Marge's eye color. Grampa reminds Homer that he once wrote a song about her. He gets through the song but still can't get the eye color (it rhymes with "appraisal".) Marge heard the song and was so moved that she removed her sunglasses, revealing her hazel eyes. Milhouse and Uncle Zack are flying in the biplane and accidentally blow up the plane. Bart's upset that Milhouse is happy again. Lisa says that Bart just misses him. She's right.
Principal Skinner informs the students that Milhouse is leaving, he and his uncle are returning to Solvang via a hot air balloon. Bart doesn't want Milhouse to go and grabs onto the rope, flying away with them. Kirk and Luanne actually survived and have crafted a hang glider to return home. They take off and crash right into the balloon. Uncle Zack radioed for help, so they all get rescued.