In the season premiere episode, "Not Your Brother's Drop Off," Sue cannot contain her excitement over getting ready to move out of the house and into the dorm to start college. But Sue's excitement starts to give way to dread when she accidentally burns her hair and ends up having to cut it short, Axl doesn't want to join the family and help his sister move into the dorm, Frankie finds herself not feeling sad about Sue moving out of the house, and Mike overwhelms his daughter with learning financial and safety guidelines to keep her safe at school. Meanwhile, Brick doesn't know what to do when his girlfriend, Cindy, tells him that she wants to take their relationship to the next level.
Nervous about starting college and disappointed that her dorm roommate has not arrived yet, Sue begins to drive Frankie and Mike crazy with her multiple texts and calls at all hours. But when her dorm roommate finally arrives, Sue naively thinks that all of her worries are going to go away and that she'll make a new life-long friend. Meanwhile, Axl and Hutch find their house being overrun by ants, and Brick finds himself being protected by his own mysterious school bodyguard.
Frankie is speechless when Mike -- whose entire wardrobe consists of long sleeved flannel shirts -- decides to wear a short sleeved Hawaiian shirt when they go out to dinner with some friends. Meanwhile, while Sue excitedly finds herself signing up for as many no-cut college clubs as she can, she accidentally tells Devin how much Axl loves her, which scares Devin and leads her to question their relationship; and Brick gets a little too ambitious while tackling his chore of cleaning the bathroom.
Frankie is completely gobsmacked when Mike's brother Rusty (Norm Macdonald) pays an unexpected visit and offers him an opportunity to partner on one of his crazy business ideas -- and Mike wants in. Meanwhile, Axl goes to extreme measures to prove to Mike that he can handle riding his dad's new motorcycle; and unbeknownst to her parents, Sue tells Brad that her college roommate is so horrible that she's resorted to living in her car.
Frankie becomes worried about Mike, who is being more quiet and distant than usual, and calls on Reverend TimTom to come over and try to find out what's troubling him. Meanwhile, Sue invites an excited Brick to spend a weekend with her at college, which includes a tour of the library. But when Sue bumps into Logan -- the hunky Abercrombie guy who had asked her out to prom -- and once again falls under his dreamy spell, she realizes that Brick is no longer with her and is now missing; and Axl and Hutch decide to take matters into their own hands by complaining to the city when their house is completely overrun with ants, and they discover that they may have even more problems than an insect infestation.
Halloween finds the Hecks in their own "Twilight Zone"-type stories, with Brick providing an introduction to each.
Frankie's excitement about homecoming dwindles when her mother decides that she's going to attend the event; Mike helps Brick compete in the tailgating cornhole tournament after Axl gets sick; and Sue volunteers as class liaison for homecoming.
The Hecks agree to forgo Thanksgiving after Frankie finds out that she's out of a job until January and must pick up a holiday position, which requires her to work on Thanksgiving in order to make ends meet. Much to her dismay, she ends up once again having to portray an overworked 19th century woman back at Heritage Village during the Harvest Feast and finds herself going face-to-face with Sheila (Faith Ford), a woman who definitely takes her job too seriously. Meanwhile, Sue goes back to work at Spudsy's over her holiday break in the hopes that she'll once again run into Logan - the dreamy Abercrombie guy, Axl finds himself in foreign territory when he starts becoming emotional over how his life has turned out, and Mike and Brick find themselves needing to find a bonding experience when the electricity goes out at the house and they are forced to interact with each other.
Frankie invites Mike to join her on an all-expense-paid trip to Des Moines where she must attend a convention as part of the dentist office's transition to a new owner, and Axl informs a disapproving Sue that he's going to move into her dorm room temporarily until he finds a new place of his own.
The Hecks attempt to stay home on Christmas Eve and watch a holiday church service on TV instead of actually attending church.
The ever optimistic Sue decides that she wants to become part of a social circle and thrusts herself head first into the college's sorority rush in the hopes of being accepted into a house. Meanwhile, Axl tries to connect Mike into social media in an attempt to help generate awareness of Mike and Rusty's baby-diaper business, and Frankie begins to feel like she's not needed as much in her son's life when Brick goes shopping for a pair of pants by himself for the first time.
Axl has big plans for his first day as a business intern at Little Betty. But his dreams of coming up with new ideas for the snack-making company go out the window when he's reduced to doing menial tasks for an ungrateful boss. Meanwhile, while having to listen to Frankie complain about how much she hates working for the new dental-office owners, Smile Superstars International, Cindy informs Mike that she has kissed another boy and that he has to break the news to Brick; and Sue's professor challenges her to stop seeing the world through rose-colored glasses and really open up and hone in on her critical thinking for a writing assignment.
Feeling guilty over floating Frankie's 50th birthday for too long, Mike enlists Axl and Brick to help him set up a surprise party for her. Meanwhile, Sue finds herself being mocked after posting a sign in the dorm laundry room to help find one of her lost socks, and after Brick turns in an "I Can't" project at school and indicates that he can't do sports, Coach Babbitt makes it her mission to turn him into an athlete.
While Frankie and Mike try to figure out which household appliance a piece of plastic belongs to, Brick becomes a tyrannical director when he casts Cindy and Troy to re-enact scenes from "Knots Landing" for a school project; Sue's excitement over having new friend Lexie become her college dorm roommate quickly sours when she finds herself being charged for half of the new things that Lexie is spontaneously buying for the room; and Axl finds himself becoming stressed out when his boss (Alan Ruck) befriends him and tells him that the fruit pie division is on the verge of being shut down.
After discovering that Brick has never seen a movie in a theater, Frankie and Mike take him to see a film with a small scene that was partially shot in Orson. But when Brick sees a trailer for an upcoming "Planet Nowhere" film that he completely disapproves of, he makes it his mission to ensure that it won't ever play in that theater - or anywhere else. Meanwhile, Frankie and Mike get into a major disagreement over how events really unfolded when Mike shushes Frankie after he perceives that she was constantly interrupting Bill while he was telling a story; Sue runs into Logan - the hunky Abercrombie guy - and thinks she has a real chance of becoming his girlfriend; and Axl and Sean discover that they have unexpected ties to an event that happened when they were young.
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.
Frankie is excited and looks forward to re-bonding and taking care of Sue and Axl, who both have to stay home during Spring Break to recuperate from having their wisdom teeth removed. And since he's the only Heck child still living at home full time, Brick tries to lay down some new house rules with his siblings during their stay. Meanwhile, Mike becomes furious with brother Rusty after discovering that his ex-wife Marlene came up with the diaper business idea and may be entitled to all profits made from the endeavor.
After making some extra money from the diaper business, Mike surprises a rather unenthusiastic Heck family with a spring break vacation at Mammoth Cave, Kentucky. In the hopes of livening up what is perceived to be a lame vacation, Frankie suggests that the Donahues join them. While Mike visits all of the attractions on his own, Nancy asks a not-so-thrilled Frankie to speak with Sean to try and talk him into taking his MCATs; Axl enlists Brick to help him pick up women by playing "Jerk/No Jerk" - with Brick in the role of the "Jerk"; and Mike is anything but excited when an exuberant Sue reveals some news to him about her upcoming summer plans.
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 is thrilled when Sue invites her for lunch at the college. But lunch becomes awkward when Sue brings her new boyfriend along - Jeremy, the school activist - and the two of them begin bombarding Frankie with everything she and the world, in general, are doing wrong. Meanwhile, Axl informs a very disappointed Mike that he wants to quit football, and Brick overly obsesses over filling out a satisfaction survey after ordering some graph paper online.
Frankie is excited to lay out and relax on her new backyard lanai - aka patio - that Mike and his workmates built for her. But peace and serenity become hard to come by when new neighbors, with three screaming kids, move in next door and make it next to impossible for Frankie to find some quiet time. Meanwhile, Brick questions Mike as to whether his workmates helped build the lanai because they are his friends, or because he's their boss; Sue and Lexie draw a winning number in the dorm lottery and score the perfect room but find it difficult to kick out its current occupants; and Axl and Hutch open up a grilled cheese food truck out of their Winnebago, with a reluctant Kenny as their chef.
After enduring year after year of botched Mother's Days, Frankie declares that the family gets to take a pass on doing anything at all for her this year. But after a man offers to buy Frankie's groceries at the market when she discovers that she forgot her wallet – and tells her to pay the kindly gesture forward – she decides to have the family pull each other's names out of a hat and do something nice for that person, which doesn't go as smoothly as planned.
Now that summer vacation has begun for Sue and Axl, and they are both back at home, Frankie and Mike attempt to set a curfew for them after they end up coming home from a party at 2 a.m. But after arguing that they don't have a curfew while away at college and won't abide by the rule, Frankie comes up with an idea that will clandestinely let her know where both of them are at all times. Meanwhile, as middle school graduation nears, Brick desperately tries to discover who he's up against for class valedictorian.
After almost forgetting that Brick's middle school graduation is only days away, Frankie goes on a mission to right a wrong when Brick discovers that the song he was supposed to sing at the ceremony has been cut. Meanwhile, Sue needs to be at Dollywood to begin her summer job on the same day as Brick's graduation, and Axl takes a job as a country club counselor and finds himself being mocked by a 10-year-old carbon copy of himself.