|Season 1, Episode 4|
|Air date||December 8, 2015|
|Written by||Eli Talbert|
|Directed by||Donald Petrie|
The doctors treat those injured in a movie theater shooting; Natalie asks Daniel for help treating a teenager with an eating disorder; a patient surprises everyone.
- Brian Tee as Dr. Ethan Choi
- Colin Donnell as Dr. Connor Rhodes
- Marlyne Barrett as Maggie Lockwood
- Nick Gehlfuss as Dr. Will Halstead
- Oliver Platt as Dr. Daniel Charles
- Rachel DiPillo as Dr. Sarah Reese
- S. Epatha Merkerson as Sharon Goodwin
- Torrey DeVitto as Dr. Natalie Manning
- Yaya DaCosta as Nurse April Sexton
- Jesse Lee Soffer as Detective Jay Halstead
- Sophia Bush as Detective Erin Lindsay
- Dora Madison Burge as Jessica Chilton
- Kara Killmer as Paramedic Sylvie Brett
- Julie Berman as Dr. Samantha Zanetti
- Brennan Brown as Dr. Sam Abrams
- Alex Weisman as Paramedic Allen Chout
- Joe Tapper as Rick Miller
- Paul Fitzgerald as Bill Simms
- Beth Chamberlin as Courtney Cole
- Gus Birney as Ashley Cole
- Daniel Mozurkewich as Peter Wallace
- Mary McDonald Kerr as Brenda Wallace
- Shannon Parr as David Wallace
- Joan Porter as Gertrude Kovach
- Sara M. Holden as Lucy Simms
- Connor Norris as Max Simms
- Miriam Lee as Paramedic
- Nick Mayer as Paramedic
- Cesar Jaime as Paramedic Cesar
- Adam Poss as Paramedic Adam
- Amanda Marcheschi as Nurse Dina
- Michael Collins as News Anchor #1
- Aaron Holland as Reporter #1
- Darinka Lora-Stepan as Reporter #2
- Catherine Dughi as Field Reporter
- Michael Kevin Martin as Patient #1
- Kathleen Puls Andrade as Patient #2
- Joie Goodman as Server
The episode begins with a family buying tickets and a massive movie theater shooting.
At the Hospital the crew are buying some fast-food for dinner, Will rejects Connor's offer stating that he gets that he is rich but he doesn't need to buy them food. April defends Connor, saying that he is just new and trying to be nice. As Natalie eats some cabbage mix her mother-in-law gave her, Will grabs her a napkin and April comments she sees something between them. However, Natalie argues they are just friends. The meal is interrupted by beeping pages and Maggie calling and informing them of the shooting.
Connor is treating a mom that served as a human shield to her son as people trampled her. She was down for too long, she is non responsive to pain and has no reflexes. Which basically means she is brain dead. The woman was also a registered organ donor, so her husband is giving permission to take her off the ventilator and harvest her organs.
It's revealed that the shooter was shot by a civilian, a high-school algebra teacher, Mr Miller. He is perceived as a hero, everyone thanks him for his quick action to shoot the perpetrator. That is, until Chicago P.D. shows up to question him and Maggie makes an interesting statement: even though it was a mass shooting they only had one shot victim - the shooter. It's possible that the gunshots he heard were from the movie as the shooter didn't have a riffle at all, it was a leaf blower. The boy was nothing more than a prankster that enjoyed making funny videos and posting them online. The toll of having shot a young boy and no longer being the hero proves to be too much to Mr. Miller, who later contemplates suicide. He stepped in front of a car and didn't survive.
Dr. Manning is treating a girl that felt dizzy before the confusion began at the Theater. Natalie suspects the girl suffers from an eating disorder because her mom talks a lot about healthy food. Furthermore, she makes a connection between the case and an old friend who died of anorexia. Consequently she enlists the help of Dr. Charles. He then gives the girl a placebo in a hamburger to prove that Natalie's conclusion was nothing more but a biased confirmation, she was reminded of the past and didn't look at the whole picture. Turns out the young girl really had a physical problem, and can be treated. She will have to wear a nasal feeding tube for a while.
Dr. Connor treats the shooter, he opens his chest and sends him to the OR. Will doesn't understand why he is trying so hard to save the boys life. The trauma surgeon is Dr. Zanetti, the two flirt during the operation. The surgery goes alright but Peter Wallace needs a liver transplant. Dr. Connor tries to get Lucy's liver for his patient. At first the husband is reluctant to give his wife liver to her "killer", but surprisingly he signs the paper. After the transplant the husband visits Peter to tell him that he will haunt him for the rest of his life. Peter wanted followers so much that he will follow him for the rest of his life in every social media he's on.
Meanwhile, April and Dr. Halstead deal with a racist patient. Her condition is treatable, however Dr. Halstead presents her with DNA results stating that the patient is part African-American.
At the end of the episode Zanetti and Rhodes are seen getting into bed together and Dr. Charles and Goodwin are drinking at Molly's.