Brick starts high school and decides he wants to change his image. Axl brings home a girl named April that he's been seeing, and Frankie notices that she's not exactly the brightest. The next day Frankie cooks a family dinner, but April and Cindy also show up. This gives Frankie a glimpse into the family's future, making her worry that their "core group" will soon be no more.

Axl and Hutch get into an argument because Axl keeps taking their motor home off-campus to visit April; while Brick struggles to swallow a pill for his ear infection, having never taken medication in pill form before. Meanwhile, Sue tries to get reinstated into college after she figures out she never renewed her tuition.

Frankie is both surprised and annoyed to hear the kids would rather live with Mike if they ever divorced. Axl begins lashing out at his family after spending so much time acting nice around April.

Frankie accidentally buys underwear with a sexy saying on the bottom. When she goes to return the item, the young salesperson angers Frankie with comments about her age, so Frankie instead buys more panties with similar sayings. Brick worries about losing a friend when the school's football coach recruits Troy. Axl vainly implies that Lexie has a crush on him.

Brick turns 15 and insists that his parents to teach him to drive, as Axl and Sue had learned at 15, but his erratic driving scares both parents so Axl lets him learn on the RV. When Brick knocks over the huge ceramic "Orson Cow" during a nighttime driving lesson, Axl convinces his brother they must cover up the crime.

Frankie fumes when Axl announces that he'll be with April's family for three different Thanksgiving meals, forcing Frankie to arrange a Heck family meal at 8:00 AM. On the eve of Thanksgiving, Brick also says that that he doesn't like April and even Mike gets mad when he learns Axl won't be back home Thanksgiving night to watch the Colts game with him. Amidst the verbal jabs, Axl walks in. Frankie finally tells him that he can do way better than April, causing Axl to leave and not return.

Several days after the Thanksgiving incident, Axl still refuses to talk to Frankie, who continues to fume. Mike visits Axl and tries to get him to relent, but is unsuccessful. The family problems trigger one of Brick's quirks, which gets him in trouble at school and earns him a meeting with Dr. Fulton. Frankie finds a store that sells misshapen produce.

Mike trips and falls when going down the stairs at the quarry. He just wants to forget the embarrassing incident, but the fall has ruined the quarry's streak of accident-free days and causes a safety trainer to be sent to the site. Frankie goes on an unintended road trip with Rita Glossner. Axl finds out April's family does not like him. At the end of the episode, he reveals that he and April got married.

Axl finally decides to return home and tell Frankie that he got married but, when he arrives, Frankie is so overjoyed to see him that he delays breaking the news, Frankie ultimately learns the truth when April's parents call, causing her and Mike to convince Axl to get the marriage annulled. Elsewhere, Brick does such a great job babysitting neighbor Deirdre's three children that the kids constantly come knocking for him. Also, Mike doesn't know how to reciprocate when Bill Norwood gives him an unexpected Christmas gift.

New Year's Day finds the Hecks lamenting that they did nothing special over the holidays, until Frankie finds an about-to-expire pass to an escape room. While leaving, the family runs into the Donahues, who brag about their record time escaping the room. This makes Frankie more determined than ever and she is confident they can beat the Donahues' time The Hecks are joined by a man named Milt in the escape room, being short of the minimum number of participants, and earns them extra time needed to win the game. Brick becomes convinced that Milt is really David S. Rosenthal, author of the Planet Nowhere books. Frankie also reveals to Mike that she had a romantic dream that involved Frank Sinatra.

Frankie is ecstatic when she wins a month's worth of free maid service. Unfortunately, she discovers that good help is hard to find. Mike learns that his father is now using a cane and can't get himself upstairs, so he and Rusty try to get him into a home, much to his annoyance.

Axl panics when he realizes that he only has four months until he graduates from college, but he hasn't sent out any job résumés – something he should have started when he was a junior. and Brick desperately seeks his parents' advice when Cindy tells him he reads too much and that she'll break up with him if they don't do more things together.

Frankie becomes sad when her doctor informs her that her ovaries are shriveled up and her childbearing years are over. Mike tries to cheer her up by borrowing Dierdre's infant overnight, which puts some perspective on being an older parent and Brick must hone his font knowledge when he meets Gibson, a worthy opponent who joins Brick's club at school.

Brick witnesses Mike and Frankie fighting under stress when the pipes in the basement suddenly burst and they have to fix the problem. He asks Axl to host an intervention for their parents. Mike and Frankie are initially remorseful about how they made Brick feel, but later decide it's the kids' fault. Ultimately, everyone learns that they need to improve themselves.

Mike does all he can to avoid getting a tooth problem fixed, which includes involving Dr. Goodwin in a series of lies to keep Frankie at bay. Axl, Hutch, and Kenny try to sell the Winnebago. Brick starts writing a Scottish musical in the style of Hamilton.

The quarry softball team is on a losing streak, so Mike hires Coach Tink Babbitt as a ringer. The team starts winning, but Tink takes over and benches Mike. Also, Nancy Donahue exclaims that Frankie must be very proud of one of her family members' achievements, but Frankie is clueless. She eventually finds out that it's because Brick made it into the National Honors Society. Back at school after break, Axl seeks out Lexie at a St. Patrick's Day party, but runs into Devin Levin instead.

Axl runs into nearly all of his ex-girlfriends while attending a St. Patrick's Day party, including Devin Levin, Cassidy, and even Weird Ashley. Hutch tells Axl that the universe is trying to tell him something about his love life and that he must speak with each of them to try and figure it out. In the fallout, Axl breaks up with April. Meanwhile, Brick purchases an old microfiche machine from a library sale and finds a "scandalous" local news article about Frankie from 1983.

Bill Norwood is so upset with Mike for poaching his plumber at a reduced rate that their friendship could be at risk. Elsewhere, Brick convinces Axl to let him hang out with him at college over the weekend, not to visit the library, but to have some fun and party. With Brick's encouragement, Axl works up the nerve to pursue Lexie romantically. .

After being reminded that Brick was never confirmed, Frankie and Mike send him to Reverend Tim-Tom's Wilderness Jesus Jam weekend camp to brush up on his religious knowledge in preparation for the blessed event. Brick is shocked to discover that his bunkmate is Blake Ferguson, the boy he was switched with at birth and was raised by Frankie and Mike for the first month of his life. Meanwhile, Axl and Lexie try to keep their new relationship a secret,

After discovering that he doesn't have a decent suit to wear for upcoming business interviews, Frankie is thrilled when Axl agrees to let her take him shopping and help him pick out a suit. When Mike threatens to tear down the family backyard pool if Sue and Brick doesn't start using it, the two begin to worry that he and Frankie may get rid of more things around the house from their childhood that they don't use anymore, as they edge towards adulthood.

Frankie has trouble remembering where she hid Axl's graduation gift, which she bought and put away a long time ago. When she does find it, it turns out to be not as special as she thought it was. Axl trains Brick to become physically stronger after Cindy has to save Brick from a bully. Axl realizes during the process that he's not as physically fit as he was when he was training for football.

After missing his final college test before he graduates, Axl pleads with his teacher to let him take it anyway. Meanwhile, Frankie, Mike and Brick all hit a stretch of good luck, and owe it to the Donahues' address number being accidentally painted on their curb.

After Kenny develops successful apps that will let him retire within one year, he asks Axl to travel through Europe with him for three months, with Kenny paying for the trip. Mike is staunchly against the idea, saying Axl needs to grow up and start looking for a job at home, while Frankie sees it as Axl getting a rare opportunity that she and Mike never had. It is revealed that Mike really wanted to spend one last summer with Axl. Brick seeks out his old lawn chair after experiencing back pain.