The doctors joke with each other as they come on shift, and Maggie invites Nat to Ladies night at Molly's in the hope of playing wing-women for April. Choi goes back to his car, only to find a man carrying a bleeding girl in the parking lot. Once she's inside, the doctors discover she's just given birth. Connor and April head out with the man to find the baby abandoned in a backpack in an alleyway. They revive the baby and take him back to the hospital.
Sarah is assigned to an elderly woman with a sprained wrist who is also exhibited signs of dementia. Will treats a man complaining of chest pain. Sarah asks for Charles' help with her patient, and he gets her contact info from her medic alert bracelet. Turns out that ladies night is really a "surprise" baby shower being thrown by Nat's mother-in-law. Nat agrees to go along with it. Nat continues treatment of the girl, Erika, who is anxious to leave the hospital. She won't let Nat call anybody for her, and is relieved that they found the baby. She's only 14, and she then asks Nat to call her sister in Champaign. On the roof, Nat, Choi, and Connor discuss the case, with Nat defending Erica and Choi blaming her for abandoning the baby. Connor tries to stay out of it.
Nat visits the baby in the NICU. Connor gets a message from his father, but throws it in the trash. Dr. Zurney blows off a drug rep, Zoe, and she tries her pitch on Will. He gets a patient, and she invites him to dinner to finish. Will discharges the chest pain after his tests come back. The wife leaves after dismissing the possibilities of anxiety and stress. Will prescribes a follow-up with a cardiologist. Nat asks Will to come to the baby shower to support her, but he bails because of his date. Dr Charles talks to "Connie's" husband about her dementia while Sarah shadows. Carol doesn't recognize her husband but Charles convinces her to go with him. On the way, she makes a comment that makes Charles think that she is suffering from something other than Alzheimers. A code blue goes off; Erika is bleeding out from retained placenta. Connor isn't happy to find out that Choi delivered the placenta and not OB.
Erika is is not doing well as the OB tries to complete the procedure. Sharon gets briefed on Erika's history -- in foster care after her mother went to prison, she's been through lots of homes, either running away or being kicked out, suspected substance abuse, arrests for solicitation. Nat briefs them that Erika is in surgery and may need a hysterectomy. She brings up the possibility of Erika and the baby going to live with the sister. The social worker thinks that Erika is likely to be charged with several crimes. Connor is upset with Choi choosing to perform the placental delivery and questions if his personal feelings got in the way of treatment. Will is paged to the ER where his chest pain patient is in cardiac arrest. Nat gets called to NICU, where the baby has a collapsed lung. Will is at an impasse with his patient, and decides to use nitric oxide to reduce the stress on his heart. But it's the same thing the neonatologist needs to treat the baby. Will finds out that Nat just signed out the last tank, and forcibly takes it from her.
Will's patient is still crashing, and the baby is but on ECMO instead. Erika's sister has arrived to meet with Nat. Charles finds Choi outside on break, and they talk about Choi's past in the Navy. Erika's sister seems reluctant when Nat brings up Erika and the baby coming to live with her. Dr. Zzurney updates Will on the cardiac patient, and tells him he would have let the patient go with such a long code time. Connor gets a page, and it's his father's chauffeur. In the parking lot, his dad says in the car while he tries to convince Connor to move on from an unknown conflict. Connor refuses to believe his father really has changed. Erika's sister leaves and Nat is shocked that she isn't willing to take in the girl. The dementia patient is given a lumbar puncture to relieve pressure -- Charles thinks shes suffering from hydrocephalus. The husband feels guilty for missing it, and Charles offers him absolution. nat gives Will the cold shoulder. Sharon tells Nat that the police are on the way to talk to Erika, and she snaps at Choi. He goes into Erika's room, and advises her on what to tell the police. The cardiac patient's wife is upset when she finds out what the long term damage to her husband may be. Burgess and Roman show up to question Erika, but when they get to the room, she's gone.
Nat bemoans her optimistic outlook about Erika and the baby, and Maggie offers to let her out of the shower. Choi asks Charles about Erika, and blames himself for her leaving. Will berates himself about missing the signs in the cardiac patient. The dementia patient wakes up, and is no longer suffering senility. Sarah explains things to her in a very technical manner, and Charles corrects her. Will calls Zoe to cancel.
Ending Montage scene.