Nat returns to work, and Maggie gives a tour to a security team. April gives Nat a respiratory distress case with no discernable cause. The father tells her that the girl has mitochrondrial disease. He is removed from the room as they start a crichotomy, and and the girl spontaneously recovers as they are about to put the needle in. Nat and April are suspicious. A Saudi royal arrives for a valve replacement with a world renowned heart surgeon at the hospital. Choi recognizes Will's patient, and takes over the case. Nat reads up on the girls medical history, and Will welcomes her back. Will doesn't believe in the mitochrondrial diagnosis, and Nat can't find any confirmation in the records. April catches Sarah being flirty with the lab tech, and April finds him while flipping through a dating app. Maggie comes over and assigns them to a drunk college girl. Choi's friend reveals that there's blood in his stool when Choi is reluctant to do a CAT scan. He finds blood when he does a preliminary rectal exam, and ends up ordering the scan. Connor is working on a stabbing victim when the heart surgeon, Dr. Downey comes in to the OR for a bizarre and brief observation. Sharon and Charles are overwhelmed by the prince's entourage. Charles is not impressed with the priorities of the hospital. Will and Nat check in on Michelle. When Will brings up the lack of biopsy to confirm the diagnosis, the father overreacts. The girl gets out of bed to eavesdrop, and passes out. Choi's friend has a large mass that he suspects to be colon cancer. Choi is outraged that the VA hadn't gotten around to doing a CAT scan despite knowing his symptoms and suspecting the diagnosis. Charles asks Will about Michele, and Will fills him in. They can't tell what are real symptoms and what are side effects of all the medications she is on. Charles doesn't feel like he can interview the family without changing the dynamic and wants to observe unobtrusively instead. Connor gets called up by Dr. Downey. Sarah finds out that Joley is still active on the dating site. The drunk girl's friend asks her about med school, and Sarah over-shares about the complications about dating in med school. Sun starts to seize, and they can't figure out why. Downey praises Connor on his private floor, and takes him to meet the prince. Sarah gets Sun's test results from Joley, but gives him the cold shoulder when he kisses her. She confronts him about the app. Downey takes Connor to the pre-op discussion with the prince, and Connor questions Downey's plan. Nat calls Helen to check on Owen. Will comes in to show her a video. They and Charles share it with Sharon -- the girl is fine when her father isn't in the room, but as soon as he comes in, he behavior changes. Sharon is outraged that Will and Charles spyed on the girl, as is Natalie. Nat wants to do more to rule out a real illness before accusing the father of abuse. They set up a way for Charles to interview her without the father around. Downey has Connor prepare his tea in "preparation" for surgery. Downey sends Connor off after he makes a connection about Downey's methods. Charles interviews Michelle about the first time she experienced any symptoms. Maggie is keeping the father busy with paperwork, but he refuses to be kept away from Michelle. Charles tries to explain his diagnosis to Mr Joffe, but he overreacts, and attempts to take Michelle from the hospital. As he tries to get into the MRI room, CFS turns up to take custody of Michelle. Choi tries to contact his friends doctor at the VA, but can't get anywhere. He decides to head on over to the VA hospital. Connor catches Sarah lost in thought over her patient, and gives her some advice. It turns out that Sun went to a club the night before with the friends bf, and drank a lot of water. Sarah orders a tox screen after the friend storms out. Choi arrives at the VA and takes his anger out on Dr. Vicky Glass. When he suggests that she should have screwed protocol, she explains how she did just that. Joely brings Sun's test results back, but she didn't have any drugs in her system. Joley says he's going to take down his online profile and one of his anecdotes sparks an idea for Sarah. Choi arrives back at Med to find his friend being taken in for emergency surgery. Nat is torn up about calling CFS, but her test results came back negative. Mr. Jaffe comes back to the ED with a police officer, claiming that they kidnapped Michelle. Sharon speaks to the officer, and he advises Joffe to find a lawyer since CFS has jurisdiction. Sarah tells Sun that she has Lyme disease. Connor updates Choi on his friend, and Choi remarks on the unfairness of the world. Charles and Will observe Joffe in the waiting room, and Charles goes in to try to apologize about how things happened. Charles reassures him when he expresses doubt that maybe he did cause his daughter's symptoms. Choi accompanies his friend to the reunion event, and he also runs into Dr. Glass, who he asks out.