Reese is feeling paranoid about being followed when she notices that Danny is watching her at the food trucks. She goes to Dr. Charles about treating him outside of the hospital, but he shuts her down. Later, he confesses his own history with a patient that he became too attached too. He allows her to treat Danny, but only if she follows his guidelines, which include meeting with Det. Lindsay about precautions to take and how to better understand Danny's world. She later meets with Danny in an alleyway, and urges him to try and leave, but she pushes too hard and he runs off. She's shocked when he shows up in the ER later with a self inflicted would to his side; rather than suicidal, he's tried to cut out the GPS chip. Choi removes it surgically and Reese disposes of it by dropping it into the water running off the street.
Choi treats a young girl with a stomach obstruction but she refuses to reveal what she swallowed. When he finishes the endoscopy, he's confused by what he found, as is Nat. It turns out the girl is a "body hacker" and her friends are "bio hackers" -- they have a lab set up in her basement where they perform all kinds of research and experiments. She was attempting to build a nanobot that could clear GI obstructions and repair the bowel wall from within. Initially disapproving, Choi pays the lab a visit and is impressed with what the kids are working on. When Nat is depressed about the loss of another patient, he sends her there. She is also impressed, and talks to the kids about maybe working on a cure for what killed her patient.
Haley is readmitted to the ER, disassociated and severely jaundiced. The chemo has damaged her liver which has in turn caused swelling in her brain. After stabilizing her, Nat and the nuerosurgeon tell the parents that she'll need a drain placed to relieve the pressure. After that is completed, Nat reassures them that Hayley will be okay. She later goes to Dr. Charles, feeling guilty about providing what is probably false hope. He tries to reassure her, but the guilt only comes back when Hayley codes and the doctors are unable to revive her. Later, on Choi's advice, she visits Shannon and her friends in their basement lab where she is impressed with the advanced work they are doing basically unsupervised.
Connor starts to doubt his abilities when Latham picks up on a heart murmer that he completely missed in a post op patient. Later, he agrees to do perform surgery on Will's patient, despite anything in the labs or test results being definitive, because he doubted earlier and Will is insisting that he felt the patients bowel dying. Nat reassures him that Latham probably picked up the murmer because he's spent time listening to hundreds of hearts. When Connor questions Will about how he caught the necrotic bowel, Will tells him about his old school teacher from med school who taught him to rely on himself instead of just diagnostic tools. Later, Will visits his old teacher in a care facility, and Connor spends the night in the medical library listening to heart beats.
When Maggie has trouble clearing the ER of patients, she finds an empty room in the post op unit that the doctors refuse to use because three patients have died there in three weeks. She combats their superstitions by calling in a friend of Connor's, the guy who owns the Hawaiian bar, to do a purification of the room.