Frank returns, disrupting life; Lip attends college; Ian is missing; Fiona tries to connect with Debbie and Carl.

Against her better judgment, Fiona continues her secret affair with Robbie. The situation nearly boils over when Mike shows up at Robbie’s apartment while Fiona is inside. Fiona is able to hide just in time before her infidelity can be exposed. 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.

Fiona ends up in jail; the family waits for news about Liam; Frank wakes up in the emergency room.

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 violates terms of her probation, sending the family into search party mode.

Fiona gets out of jail. Frank is feeling like his old self.