Picking up in the middle of the scene from Chicago Fire, Connor and Zanetti take Hermann into his second surgery. There's some question over whether Connor's earlier decisions led to this new crisis. Sarah has an awkward encounter with a strange lab tech over Splenda at the coffee cart. Choi treats the Jessica Pope, the victim from the Fire episode. He reveals to Sharon that it looks as if she has undergone chemo. Severide and Jay come to check on her, bringing her belongings. Sharon asks Charles to go through her things to try and figure out if it was a suicide attempt or not. Lindsey shows up with the news that there's no evidence of foul play at the apartment. At Severide's urging, Jay asks Will if he would have done anything different with Hermann's treatment than Connor did. Will tries to previcate, but when Jay pushes, he admits he would have done things differently. Maggie reminds Natalie about their appointment to tour the maternity ward, which Natalie is reluctant about. Jay approaches them, and is confused that Nat is going to treat an 80 y.o. woman since she is a pediatrician. Maggie explains her program, and Natalie questions Jay about what else Will has shared about her. She goes to check on her patient, whose son is with her. He can't tell Nat much about his mother's condition other than that she's been being treated for oral cancer as he has been living elsewhere. April introduces her little brother, a third year medical student starting his ER rotation, to the staff. Sarah agrees to show him around. She checks in with Choi to see if she can run some tests on Jessica, since she fits the criteria for her research. Charles approaches Will to see if Jay could do some more digging on Jessica's case, since the lack of suicide note is not in line with what one would expect. Sarah takes Sexton around, stopping at the lab where she encounters Splenda guy, Joey. She awkwardly tries to get him to run her labs stat for her, and he agrees easily. Jay told Severide about what Will said, and now Severide shares this with the rest of 51 as they watch Connor check on Hermann. Severide goes into confront Connor, who is affronted. Connor asks Zanetti if she was the one to talk to the firehouse about him mishandling the case, which offends her. Jay agrees to take another pass at Jessica's case once Will agrees to buy him some smoked trout. Choi and Sexton catch an incoming GSW. Choi asks Sexton what they should be looking for and doing as he treats the patient, but Sexton repeatedly freezes. Choi reassures him that it's not the last GSW he'll see, but Sexton is visibly upset. Natalie is at a loss with her elderly patient, who is worsening. The strange lab tech comes with the test results and reluctantly hands them off to Sexton when Reese is not available. Severide visits April in the ER, and is shocked to find out that Noah is a student there. They get into the elevator and start making out. Kelly invites her to dinner that evening and she agrees. Noah takes Choi Sarah's test results, taking credit for her work in an attempt to impress Choi. Jay shows up with some more info on Jessica Choi -- the document lab restored some papers, one of which turned out to be a suicide note. Charles and Will are surprised that the suicide was unrelated to her illness, but was because she felt betrayed. Choi comes up and reveals that the chemo was killing her, and that she never had cancer. On the maternity ward tour, Natalie keeps making snarky comments to Maggie under her breath. When the tour guide confronts them about her behavior, Maggie responds with a technical inquiry and proceeds to dress the guide down. They leave the tour early. Connor apologizes to Sam about doubting her. Brett brings in a patient who had a seizure while crossing the street and was then struck by a car. Will and Connor disagree on her treatment, and April finds a chemo port on the patient. Connor confronts Will about sharing his opinion with the firehouse. The patient ends up dying on the table, to her partner's distress. Sarah finds out about Noah's deceit and is pissed. He gives her a half-assed apology. She insists that he tell Choi what he did. Natalie tries to avoid her patient's son, and Will asks her to talk to his patient's partner (in an utterly tactless way). She eventually agrees. Charles and Sharon talk to Connor about the strange coincidences in the ER with the "cancer" patients. Will confronts Jay about sharing his opinion with the firehouse, and Jay tells him he shouldn't ask him any more police favors. Nat's patient starts to crash, forcing an intubation. Charles checks in with her about Carol, thinking she might be part of the pattern. Noah is struggling with his studies, and pleads with April to help him study. She reluctantly agrees. Gabby checks in with Connor when Hermann starts to crash. Severide questions Connor as he tries to treat Hermann, and Connor stands up to him. He stabilizes Hermann and gets a call to Dani's autopsy. Charles reveals that Dani never had cancer, just like Jessica Pope. The doctors and Sharon review the facts of the chemo overdoses, and make plans to further investigate. April cancels on Kelly to help Noah, which he doesn't take well. He thinks she should have been the one to go to med school. She points out that in her family, it was always going to be the boy whose education was prioritized. She tells Kelly to stay out of it and that she's capable of handling this on her own. Joey shows up to tell Sarah that another round of mass spec labs were ordered. She tries to thank him for getting the results back to her so quickly earlier, but he walks off mid conversation. Nat's patient starts to wake up, and her son is overly concerned with her care out of guilt for not being there before. Nat, Sharon, and Charles get the results back that Carol never had cancer either. Sharon has called PD in to investigate.