It's a hot summer's day in Royal Woods. At the community pool, Lincoln comes out of the changing room in his orange swim trunks, and says to the viewers that on a hot summer day, there's nothing like swimming in the pool. He attempts a cannonball, but a lifeguard stops him, and kicks Lincoln and all ten of his sisters out of the pool. Lynn, Jr. complains that they were just having fun, but the lifeguard states that chicken fighting in the pool during senior citizen swim is not fun. The family then goes to the community pool in Huntington Oaks, where Lincoln comes outs and attempts another cannonball, only for the lifeguard to kick them all out once more. Lana is called out for drinking the pool water, which she says tastes like chicken noodle soup. The lifeguard concedes to this, but scolds her for throwing carrots and celery into the pool too. Then, at a third pool in Hazeltucky, an irritated Lincoln comes out of a changing booth, and attempts another cannonball, only for everyone to be kicked out yet again. Lori complains that they were only having fun, only for the lifeguard to complain about Lily having had a fecal incident in the pool, which has now been emptied for cleaning.
The siblings are walking home, and Lori says to everyone that they can find another pool to cool off in, until Lisa informs them that they have been banned from every pool within a 60-mile radius. This angers the siblings, and causes an argument, as Lincoln laments that there's no more pool-time for the Louds. Upon saying that he has an idea and leaves while his sisters continue to argue. At a sports store, Lincoln sees a box for a deluxe pool and imagines himself swimming in it, only for his sisters to have taken over and preventing him from getting in. Cursing his inability to enjoy the pool in his own fantasies, he sees another box saying "Paradise For One", and imagines himself having the pool all to himself. He leaves with his new pool, only to realize he forgot to pay when the alarm goes off. Back at the Loud House, the sisters all cool themselves with various things from the fridge. Lincoln hides, but Leni spots him, and asks if he wants to "chill" with them. He opts not to and sneaks out the back door with his new pool set, and Lisa passes off his odd behavior as heat stroke. Lincoln opens the box and looks at the manual, only to see it's too large, and tosses it away. Lincoln tries setting up the kiddie pool, but folds it into a tent, a boat, and a unicorn.
Lincoln finally uses the instructions and uses a pump but some air deflates. He then tries blowing into it himself, but hyperventilates, becomes dizzy, and briefly falls unconscious. Sometime later, he wakes up, with half his face sunburned; he uses another pump and successfully inflates the pool. A bee appears and chases Lincoln, and it punctures a hole in the pool. Lincoln tapes the hole and fills the pool with water, but tries to move it out of the shade and fills it again when he spills it all.
Finally done (and healed from his sunburn), he comes back outside to do a cannonball, but stops when he sees Lori and Leni relaxing in it on floaties, much to his surprise. Lori commends him for buying their own pool that nobody can kick them out of, and Leni says there is room for one more if he wants in. Lincoln begins to explain that the pool was meant only for one when Lynn pounces him and calls for another chicken fight. Before long, all of the sisters are outside enjoying the pool while Lincoln struggles for a chance to finally get in as well.
While chasing Lily around the pool, as she had again ditched her diaper, Lincoln sees that Lisa is about to dip one of her experiments in the water. She explains that she's testing the water with a serum for eliminating urine. Lincoln doesn't believe anyone here would actually pee in the water, but Lisa pours it in and all the water turns purple, dissolves, and then evaporates. Everyone, save for Lincoln and Lisa, blushes with embarrassment, indicating that they all peed in the water. Lincoln rinses out the pool, refills the water and the ten sisters resume the fun. Lana is seen chopping carrots, Leni and Luan are playing "Marco Polo" while Leni gets confused with the rules, much to Luan's annoyance. Lincoln tries getting in, but he see Lily without her diaper and he quickly puts it back on her.
Before getting in, he is shocked to see Lucy in it, Lucy states she's not swimming, she's trying to see if she's a witch by floating. Confused, Lincoln says she is indeed floating, which Lucy thinks is "wicked". Again, Lily is seen without her diaper and he gives chase. Lynn and Lana duel each other with pool noodles, while Lola whines that they are splashing her. Lincoln scolds the two of them for horseplaying, until Luan suggests elephant play instead when she blasts him with water out a pool noodle which amuses the sisters.
Bobby then arrives on the scene, and tells Lincoln that Lori hired him as lifeguard. He whistles to tell everyone to get out of the pool because of senior swim, much to the outrage of all the siblings as there's no elderly people present. Lori clarifies that it's meant for her, as she's a high school senior, and says now it's truly paradise for one. Incensed, Lincoln blows Bobby's whistle and angrily tells his sisters that this was his pool that he bought, and that he hasn't even been able to enjoy it himself yet. Lynn says that they were all just having fun, but Lincoln kicks them all out, much to their anger/distress as they reluctantly do as he says.
Lincoln tries to enjoy the pool alone, but he quickly gets bored and lonely and imagines the antics of his ten sisters. He tries to do a cannonball but finds that his pool is not designed for them, much to his disappointment. He begins to regret his outburst until he hears a commotion out front, and sees that the ten sisters and Bobby are having fun playing in the new deluxe pool that they bought for themselves. Lincoln asks how they got it, and Lori begins to explain that they paid for it together when Luan chimes in to say they "pooled" their money for it, earning her another round of groans and a whack on the head from Lynn's pool noodle. The sisters invite him in, much to Lincoln's surprise as he had kicked them out of his. They say that what he did was selfish, but that they are more than happy to let him use theirs as it's more fun when all eleven of them are together. Touched by this, Lincoln happily obliges and comes in to do a cannonball. Ironically, Lincoln (nor the others) doesn't see a label warning against cannonballs INSIDE the pool, thus destroying it and causing a tidal wave.
Luna laments that there's now no pool for the whole summer, and Lori ask how they're going to cool off now. Lincoln invites them all to come back into his pool. Back at the backyard, The siblings and Bobby are all in the kiddie pool; cramped, yet cool downed and happy. Lincoln says to the viewers it turns out that a pool; and basically everything awesome in life, is more fun when everyone gets to be a part of it. Bobby quickly blows his whistle and informs The Loud Family that Lily has had yet another fecal incident in the pool, causing the siblings to panic and jump out, with Lily giggling to herself.