Will and Nat are still reeling from Will's betrayal of Nat's patient's family when Maggie assigns them to a lymphoma patient. The man is terminal -- his tumor is too large to operate on and there's no time for traditional chemo to work. Nat finds some anecdotal evidence for a new off-label cocktail of drugs. Will shuts her down, pulling rank to do so. Nat goes behind his back and offers the drugs to the man and his wife, being clear about the risks. They agree. Will is upset that Nat circumvented him, but when the patient dies hours later, he takes the fall with Goodwin. This upsets Natalie further, which confuses Will. Nat points out that he wouldn't have done the same thing for any of her male colleagues. The autopsy later shows that the patient's death was unrelated to the drugs and that the tumor had actually shrunk in the short time he received the cocktail. The oncologist ignores Will's attempt to give the credit to Nat, and she slips out of the lounge. Will follows her out to the parking lot and attempts to apologize. She stops him, pointing out that their romantic relationship is causing problems for her at work, where she already faced an uphill battle due to her gender. She ends the conversation by telling Will she needs a break from their relationship. 

Sarah is grappling with the implications of her father's diagnosis and what that means for her. She's upset with Daniel for not telling her, even while she understands why he couldn't. When the pair is called to Goodwin's office to consult about who could have taken the missing baby, she disagrees with her mentor, projecting her own issues onto the situation and hypothesizing the kidnaper could be a psychopath. When they finally find the baby and the woman who took him, she has no compunction about lying to the woman, but later worries that that is a sign she shares her father's pathology. Daniel reassures her, pointing out all the qualities that led to him recruiting her for the psychiatry residency.

Choi is over his head with a patient who was stabbed through the heart in a bar fight -- with the hospital locked down, there are no surgeons available, so he has to crack the man's chest in the ED. When things get tricky, April facetimes Connor, who is at a hospital fundraiser with Ava and his father. The two surgeons try to advise Choi, but there are complications. Ava stays on the line at the fundraiser, while Connor heads to the hospital. The cops won't let him in, but a security guard shows him an old forgotten tunnel entrance. He gets to the ED in time to help Choi with a second injury to the heart that had been missed earlier. 

At the fundraiser, Connor's dead flirts with Ava, but back at the hospital the two share a moment. 

Noah is treating a car accident victim, but is on another floor of the hospital when she has laryngospasms and can't breathe. There are no doctors around due to the lockdown, and Maggie tries to intubate her. That doesn't work, so the charge nurse crics her, even though it's against hospital policy. The patient survives, but suffers an ischemic stroke. Sharon is forced to suspend Maggie.