Fiona is balancing her job and a crush on her older boss. Meanwhile, Lip leaves college and heads back home to work a demolition job, Frank unveils the secret project he's been working on, Ian helps a pregnant Svetlana take care of baby Yevgeny and Kevin plays stay-at-home dad when Veronica goes to work at the Alibi.
Frank tries to talk Sheila out of an offer from two lesbians who want to buy her home and begins warning everyone of the neighborhood's impending gentrification. Meanwhile, Lip starts his first day of work, Kev bonds with Svetlana, Ian plots revenge with Mickey and Mandy against a homophobic military funeral protest and Fiona officially comes off house arrest.
Frank tries to scare off the two lesbians who are buying up property in the neighborhood. Meanwhile, Debbie throws a wild party, Fiona agrees to go to a concert with Davis, Carl discovers a hidden talent and Ian goes on a crazed cleaning spree and asks Lip to help convince Mandy not to move to Indiana with her abusive boyfriend.
Frank arrives at Lou's to pick up his six figure insurance settlement and is shocked to learn that he's already collected it. Meanwhile, Fiona and Gus continue to hit if off, so much so that Gus admits he's falling in love with her.
Meanwhile, Lip visits Amanda and her family at her luxurious house in Miami. Carl starts a new job as a drug dealer but quickly realizes he's in over his head. Ian goes overboard when he starts stealing suitcases from the airport baggage claim.
Fiona and Gus must navigate the awkwardness of their quickie wedding. But Fiona's plans to announce her marriage at a family dinner become unraveled when her coworker, Jackie, OD's on heroin.
Meanwhile, Frank, who promised an irate Sammi a new trailer once he got his insurance money, avoids her by staying with the still grieving family of his donor liver. Debbie continues training at Derek's gym while Carl continues to struggle with the mathematics of selling drugs. Mickey grows more concerned with Ian's erratic behavior and asks Lip what to do. And Lip makes the tough decision to head back to school early.
Also, Veronica, still feeling guilty about getting off with a guy at a club, sends Kevin out on a mission to get a handjob so that they can even the playing field.
Fiona is thrown in to chaos by the return of Jimmy/Jack/Steve, but she must deal with an even larger crises first as Ian, in a full psychotic break, steals Mickey and Svetlana's baby, Yevgeny, and takes him along on a road trip. But Jimmy is relentless in his pursuit of Fiona who, despite her recent nuptials, eventually gives in to their fiery chemistry and long history.
Meanwhile, a vengeful Sammi takes over the Gallagher house and enforces strict curfews and no amenities for Frank. Debbie starts high school where she is once again rescued by her knight in boxing gloves, Derek. And Veronica grapples with her decision to separate from Kev.
Also, Sammi's tough love on Frank takes a near-fatal turn when she stops reminding him to take his anti-rejection meds. And Ian's road trip is ultimately cut short by a psychotic confrontation with the police and, in the end, Ian finally commits himself to a psych ward.
Ian begins to regain some of his senses - and finds himself under a mandatory hold at the psych ward. Meanwhile, Sammi is forced to take drastic measures to teach Frank a lesson. Plus, Fiona makes a decision regarding her potential romantic futures with Jimmy and/or Gus, Lip learns that his tuition is short twelve grand, Carl seizes an opportunity to make Chuckie his slave, and after V moves out, Svetlana moves in with Kev in exchange for the performance of some odd 'wifely duties'.
Fiona is confused by the status of her relationship when Gus announces he's leaving to go on tour. Meanwhile, Carl is asked by his boss to run drugs to Indiana; Frank sees a way to get revenge on Sammi by using Chuckie as the mule and having him busted; and Lip, still in need of tuition money, convinces Kev to come to the dorms and sell drugs. Plus, as Ian refuses to accept his bipolar diagnosis, Debbie is tasked with minding his new meds.
Frank has a check-up with his uptight doctor, Bianca, who's cracking up after getting a terminal cancer diagnosis. Discovering she hasn't truly 'lived', he agrees to be her tour guide to the seedier side of life. Meanwhile, Fiona preps an uncooperative Carl for his sentencing hearing. Plus, Lip sleeps with a professor on the assumption he's only days away from being kicked out, Ian realizes it's time to get back on his meds and Kev finds himself enjoying college life as campus 'rapewalker'.
Frank is having a ball with Bianca, his new sick friend and formerly uptight doctor. But when Bianca thinks Frank might be developing feelings for her she kicks him to the curb. Frank, however, returns to put up a fight.
Frank grows concerned as Bianca's behavior becomes increasingly more erratic and dangerous - but he'll do just about anything to show her a great time.
Season Finale- Fiona reunites with Gus after he returns from his tour, but she struggles with the fact that her feelings for Sean have turned into love. In Costa Rica, Frank has love struggles of his own while he works to keep Bianca happy.