As we catch up with the Gallagher clan, Fiona is dividing her time between caring for the household and working at Worldwide Cup with her boss/boyfriend Mike Pratt. While her job and relationship are going smoothly, life at home is thrown into a state of upheaval with the reappearance of a drug-addled and deathly ill Frank. With Lip off at college and Ian still missing, Fiona attempts to connect with Debbie and Carl, who are dealing with the upheaval of their adolescent hormones (or lack thereof).
Fiona begins to enjoy the perks of living life just above the poverty line. She uses her newly activated health benefits to take the kids for checkups. However, when a road rage incident damages the company car, Fiona tells a much bigger lie about how it happened. Meanwhile, Lip seems to have lost his mojo as he struggles in school and with the ladies.
Frank stalks his previously unseen daughter, Sammi, and is surprised to find out she has a son, Chuck. Meanwhile, Fiona and Mike are getting serious. Also, Carl begins stealing dogs and holding them for ransom so that he can earn some drug money for Frank. Sheila has her first successful online date with Native American cowboy Roger Running Tree.
Against her better judgment, Fiona continues her secret affair with Robbie. But the situation nearly boils over when Mike shows up at Robbie's apartment while Fiona's inside. Frank, in increasingly dire health straits due to liver disease, attempts to contrive an "accident" that will provide an ample insurance payout to cover the cost of a potential transplant.
Fiona's series of bad decisions involving Robbie finally boil over. Meanwhile, Frank and Sammi pursue a cure for Frank's liver trouble and try to catch up on missed father-daughter time; and Lip gets a surprise visit at college from Army investigators.
The aftermath of Liam's accident lands Fiona in county jail, unsure of Liam's condition or her future. The family, minus Frank, wait nervously for any update on Liam's status at the hospital. Meanwhile, after almost being killed by the sweat lodge, Frank wakes up in the emergency room and gets some sobering news about his declining health.
The Gallagher clan deals with some changing dynamics in the aftermath of Fiona's release from jail. With Fiona under court order to remain inside the house and Frank's illness keeping him out of commission, the weight of guardianship duties falls squarely on Lip's shoulders. Simultaneously struggling to keep up with responsibilities at school, he gets some unexpected assistance from Amanda, his roommate's girlfriend.
Fiona prepares for a visit from her probation officer and must rid the house of all suspicious items, a mission that puts her directly at odds with Debbie and Carl. Meanwhile, Ian gets kicked out of Mickey's house by a hammer-wielding Svetlana, and finally makes his long-awaited return to the Gallagher house.
Carl connects with a girl in detention; Lip and Amanda grow closer; Sheila returns with big plans; Fiona searches for a job; Mickey spends time with Ian.
Fiona goes wild and violates multiple terms of her probation by partying with Robbie's degenerate friends. A search for her gets underway when she fails to contact anyone.
Fiona is taken to a correctional facility; Frank wakes up from his operation suffering from post-operative delirium; Ian crashes the christening for Mickey's son; Amanda's parents bribe Lip to stay away from their daughter; Debbie meets an older student with a dark ulterior motive.
Sheila fights for custody of the Native American kids and clashes with Sammi over where they will all live once Frank is released. Meanwhile, Fiona passes a drug test, gets released from jail and lands a job at Patsy's Pies with the help of her parole officer; and Frank begins to feel again like his old, troubled self.