One of Ethan's neighbors stabs another, and he refers the case to Dr. Charles. After the suspect's friend shows up, Daniel becomes suspicious that she was manipulated into stabbing her neighbor. He determines that the friend is a psychopath using the woman for her own purposes, but because the woman confessed to the stabbing, she's still arrested.
Daniel also treats Sarah's father, who is looking to reestablish a relationship with her. Initially, Charles thinks that Sarah reconnecting with her father is a good idea (although he refuses to giver her his advice when she asks). But when Sarah comes back from the initial meeting overly enthusiastic and sympathetic towards her father, he becomes suspicious. Sarah's dad all but confirms his suspicions when confronted; he has burned all the other bridges in his life and has no one else to care for him as his health fails. He also admits to being able to use her financial help. But Papa Reese isn't stupid -- he makes sure that Daniel is sworn to secrecy through doctor patient confidentiality.
Nat goes off on the uncle of an infant girl with whooping cough after finding out that he refused to have his son vaccinated. She also throws him out of the waiting area, insisting that it's not safe for an unvaccinated child to visit a hospital. Will recognizes this behavior as mirroring his own.
Noah misdiagnoses a patient as having a heart attack instead of an aortic dissection. Ava is outraged, but Connor attempts to mentor the younger doctor through his mistake (which was overseen by Stohl, not that that is mentioned later on). Ava and Connor manage to save the patient, which Latham finds impressive. He informs them of an ambitious upcoming procedure -- separating conjoined twins -- and implies that only one of them will be invited to join the prestigious team. They relieve their stress by finally making out.
Maggie refuses to go to Barry's arraignment, despite Nat's argument that he only got caught because he used a gun to save her life (an inane argument because using he gun didn't do anything but escalate the situation and injure another innocent bystander) . He visits the ED later and Maggie (again) points out that he had a million opportunities to explain the situation to her over the course of their relationship and didn't.