As Sue desires to join a sorority, Frankie feels useless when Brick decides to go shopping by himself. Axl helps Mike to use social media for his project.

Mike enlists Axl and Brick's help to throw a surprise party for Frankie's 50th birthday. Meanwhile, Sue is mocked after posting a flyer for her missing sock in the dorm laundry room; and Coach Babbitt is determined to turn Brick into an athlete after he turns in a project about how he can't play sports.

Sue discovers that she's too poor to keep up with her new roommate's spending habits, Axl discovers that befriending the boss isn't what it's cracked up to be, and Brick could lose his only two friends when he becomes a director.

After Brick attends a Bar Mitzvah and questions when he'll officially become a man, Mike attempts to help him become more responsible in his quest to manhood. Meanwhile, Sue exudes a little too much enthusiasm as she tries to flirt and find herself a boyfriend, and Axl and Hutch find themselves a new home in the form of a Winnebago.

Sue develops a huge crush on one of her college professors and goes to extremes to get him to notice her, and Frankie and Mike agree to meet Brick's girlfriend Cindy's parents, who end up being just as quirky as their daughter.

Frankie's plans to have a peaceful backyard lanai are ruined by her new neighbors' loud children. Axl and Hutch begin a new food business on campus. Sue and Lexie make plans for next year after they win the dorm lottery.

Mike tries to help a devastated Sue get back into college after discovering she has been kicked out for not renewing her financial aid, and Frankie attempts to teach Brick how to swallow a pill when he gets sick.

A clueless Sue turns to Axl for help in figuring out how she can break up with her boyfriend; Brick's attempts to make friends in high school are foiled by his best friend, Troy; Frankie unintentionally buys underwear with a lewd graphic.

Frankie is upset that Axl refuses to answer her calls or texts after she unintentionally admits her true feelings about his girlfriend April. Brick forms a tick in the form of a phrase that causes him trouble; Brad surprises Sue.

Frankie wins a free maid service for a month and is excited for the break, but the Heck household might pose a bigger challenge than she expected. Mike and Rusty's dad, Big Mike, begins to have trouble taking care of himself.

Frankie becomes sad when her doctor informs her that her ovaries are shriveled up, which means her days of having kids are over. In an attempt to cheer her up, Mike offers to have him and Frankie babysit the neighbor's baby overnight, which puts some perspective on being an older parent. Meanwhile, Sue and Axl are a bit shocked when romantic sparks fly between Sean Donahue and Sue's roommate Lexie; and Brick tries his best to hone up on his font knowledge when he meets Gibson, a worthy font opponent.

Frankie gets Mike to go see the dentist about his toothache, and the two collude to convince her that there's nothing wrong with his teeth; Axl, Hutch and Kenny decide to sell the Winnebago; Brick works on writing a historical musical.

Lexie joins the Hecks for their spring break plans where she confesses to Sue that she has a crush on Axl; Mike hires Coach Babbitt as a ringer to help the quarry softball team; Frankie tries to figure out the root of an underhanded comment.

Axl is startled to run into nearly all of his former flames at a St. Patrick's Day party leaving him to wonder if it is a sign about his love life; Brick buys an old microfiche machine at a library sale, leaving Frankie and Mike less than thrilled.

Mike's friendship with Bill Norwood is in jeopardy after Bill gets angry when Mike poaches his plumber at a reduced rate; Frankie is disappointed when Sue refuses to tell.....

Frankie and Mike send Brick to Reverend TimTom's Wilderness Jesus Jam weekend camp to brush up on his religious knowledge in preparation for his confirmation, but Brick discovers his bunkmate is the boy who he was switched at birth with that was raised by his parents for the first month of his life.

Frankie, Mike and Brick begin to notice that their luck has changed dramatically for the better after the Prairie Scouts accidentally paint the Donahue's address on their curb; and after missing his final college test before he graduates, Axl pleads with his teacher to let him take it, otherwise he won't be able to graduate. Meanwhile, Sue confides to Brad that her sophomore year in college was kind of a letdown. But a chance to speak to students at her former high school about college life leads her to a realization about her status as a student while at Orson High. A talk with Brad leads into an impromptu musical number about Sue's many accomplishments over the years.

After Frankie gives neighbor Nancy Donahue an old scarf that is just sitting around gathering dust, Nancy returns the favor by baking her a delicious apple pie. Believing she’s stumbled upon a way to get free and tasty meals, Frankie makes it her mission to find miscellaneous items around the house to give to her in exchange for some culinary delights. Meanwhile, Sue and Lexie prepare to move back into their college apartment but find that it’s been sublet to a man who refuses to leave; and Axl’s new job as the school bus driver gives him a chance to see how Brick’s high school sophomore year is treating him, and he discovers that Mike has refused to speak to Brick’s class on Career Exploration Day.

Frankie is worried about meeting Lexie's rich parents. Brick discovers that he can't get arrested when he participates in the school's Sophomore Slammer fundraiser.

Frankie discovers that a woman had died in the bathtub of the Heck house close to 50 years ago.

Frankie's mom stays with her after becoming ill; Sue suggests to Sean that they should set each other up on dates; Axl and Brick ponder what Mike actually does at the quarry.

Frankie decides that she needs to find something new that she's passionate about—life's third act—and Reverend TimTom offers the perfect solution. Meanwhile, tired of hearing Sue and Brick argue because of the giant hole between their bedroom walls, Mike orders them to fix it; and after Axl refuses to let rich girlfriend Lexie pay for some extravagant outings, Lexie finds a way to fool him into thinking he's becoming lucky when money and other items suddenly make their way into his hands.

Frankie has to force Brick into asking Cindy to the high school prom but worries that his quirkiness could spoil the happy event; Lexie talks a clueless Axl into giving Sue a belated 21st birthday present; and Mike becomes frustrated over how to get used to a new TV remote.

Frankie makes it her mission to sway Axl from taking the job in Denver; Sue is depressed over Sean leaving for Ghana; Brick buys a huge amount of lawn chairs to replace the one he's been using for nine years.

After nine hilarious and heartfelt seasons, a Heck leaves the nest as the family takes a road trip to Denver, where Axl will start his new job – and new life away from home.

The series concludes as the family escorts Axl to Colorado. Meanwhile the long affair of the snow globe and its relation to Sean and Sue's relationship comes to a head.