4. Strangers on a Train

Fiona (Emmy Rossum) continues her affair with Robbie (Nick Gehlfuss), who initiates a sexual encounter with her on the subway. Sammi (Emily Bergl) prepares to have herself tested so she can donate her liver to Frank (William H. Macy). However, Frank is told that as he has no insurance, he must pay $150,000 for the transplant to get it as soon as possible. To give Frank a large insurance payout, Carl (Ethan Cutkosky) breaks his leg and makes it look like an accident.

Mickey (Noel Fisher), angered by how little Svetlana (Isidora Goreshter) is being paid, tells her and all the other prostitutes not to work until they are paid more by their employer. Mickey's efforts prove unsuccessful when the women are replaced within a matter of hours, much to Svetlana's dismay. At college, Lip (Jeremy Allen White) arrives late to a test, and the teacher refuses to let him take it. Angered, Lip smashes some cars in the parking lot and flees from campus security guards. He later visits Mandy (Emma Greenwell) and they reconcile before having sex. Lip jokingly suggests Mandy not take the pill, but Mandy is upset by the idea. Lip also reveals his plan to drop out, causing an argument. When Lip calls her a skank, Mandy slaps him, causing him to storm off.

Fiona visits Robbie at his apartment to make it clear their affair is over, but eventually succumbs and they have sex again. However, they are interrupted by the arrival of Mike (Jake McDorman), forcing Fiona to hide throughout the apartment. Debbie (Emma Kenney) decides to send nude photos to Matty (James Allen McCune), but he is shocked and deletes them. To reduce costs, Kevin (Steve Howey) hires Mexican workers at the Alibi Room. When Lip arrives complaining about his life, Kevin tells him to grow up and improve himself, claiming he believes Lip can overcome the system.

Mickey visits Kevin, suggesting he can use an unused room for Svetlana and her co-workers to provide a " rub and tug " service; Kevin considers the idea. When Frank visits Sammi, she reveals that her blood type is not compatible with Frank's blood, which means she cannot give him her liver. An irate Frank goes on a rant, accidentally revealing he is her father. A shocked Sammi angrily kicks him out. However, she later meets with Frank at the Alibi Room; Frank apologizes, and Sammi decides to be a part of his life, wanting to get to know her father. Lip returns to college and convinces his teacher in letting him take a retest.