10. Nana Gallagher Had an Affair

With Monica now taking care of the family, Fiona moves in with Steve next door. Despite Steve asking her to not think of her siblings, Fiona regularly checks on them. Monica is struggling to keep up with the daily needs of her family, and Roberta makes it clear she will not take care of six children.

Frank is still waiting for Monica to sign the papers to get the settlement money, but she wants the sole custody of Liam. During this, he is harassed by a man, Jasper, a disability worker who is trying to prove Frank's disability fraud. To get rid of him, Frank makes a scheme wherein Jasper hits Carl with his car, forcing him to stop his pursuit of Frank. Monica and Roberta get a paternity test to favor their case, but are shocked when the test reveals that Liam is Frank's son. As they leave, Lip and Ian enter the clinic to get a new paternity test.

Eddie takes Karen to the purity ball, promising to buy her a new car. When the host invites Karen to open up about her past, Karen relates her extensive sexual history. An angry Eddie scolds her, calling her a whore in front of everyone. A furious Karen returns home and destroys his basement, crying to Sheila over Eddie's lack of affection. Monica informs Frank that she will sign the papers if he gives up Liam's parent rights, which he strongly considers. Fiona and her siblings criticize Frank's actions; Lip slaps him and Fiona threatens to cut contact with him if he gives up Liam. Ian visits Mickey, who has been staying in prison. Mickey does not want his homosexuality disclosed, and prefers to be behind bars.

The Gallaghers meet for dinner, where Frank and Monica get into another argument over their planned divorce. Lip arrives with the paternity tests and is surprised by the results; while Lip is Frank's son, Ian is actually the son of one of Frank's brothers. Fiona makes it clear the family does not like Monica, and states that if Monica truly loves her children, she will leave Liam with his siblings. Angered over Eddie's actions, Sheila furiously follows Eddie out of the house, overcoming her agoraphobia in the process. Frank notes that she has left her house, and she enthusiastically celebrates. Monica and Roberta prepare to leave the city, but Monica decides to leave Liam with Fiona. As she leaves crying, Fiona nods in approval.