Three concurrent surgeries at the hospital push its staff to the limits. Determined to ease the pressure, Nic requests Jude for one of the operations, making Conrad jealous. Meanwhile, Dr. Lane Hunter sets out to discredit Nic's claims, Devon struggles with a patient who has an embarrassing problem and a charitable contributor comes to the hospital wanting to donate a lot of money to Dr. Lane's oncology program.

Devon and Conrad race against the clock to save the life of a woman who is deteriorating fast from undetermined symptoms. When the patient turns out to be a hero who helps previous criminals get their lives back together, the team relies on her family of ex-cons to help diagnose and treat her. Tensions rise as Nic continues her search for evidence to incriminate Lane, but must simultaneously tend to her sister, Jessie, who is rushed into the ER. Meanwhile, York returns to the hospital with his mother, who is in need of a risky procedure, and comes face-to-face with the stone-cold Dr. AJ Austin.

A blackout at Chastain Memorial Hospital requires the staff to treat their patients without the help of any technology. Bell orders the staff to stop accepting new patients and transfer those on life support, but when a child in need is rushed to the ER, Conrad and Devon go against the mandate. Meanwhile, Mina and Austin are tasked with performing heart surgery on a premature baby, despite the lack of power, and Nic works tirelessly to organize the staff and patients who stay during the blackout.

Halloween at Chastain proves to be just as spooky as ever when Conrad is tasked with diagnosing a young woman admitted to the hospital with extreme night terrors. Meanwhile, Devon faces his first Halloween in the ER, Nic panics over her decision to bring her newly sober sister to Mina's epic annual Halloween party and Bell finds an interesting way to make use of his new assistant.

When a nasty flu season turns out to be masking a terribly infectious disease, Chastain must race to quarantine and diagnose infected patients. Mina finds herself testing Quovadis medical devices in an effort to defend Dr. Austin, who, feeling responsible for the death of a patient, is serving penance by staying away from the OR. Conrad is prepared to take the next step with Nic, but finds that she may not be as ready.

Bell hopes that a lottery winner who was admitted to hospital could serve as a way to solve Chastain's financial struggles; Nic is irate with Alec for suggesting she meet an organ broker; Devon and Irving help Mina remember certain details.

When a police officer brings in an injured criminal, the staff must keep him alive. Nic gets roped into a surgical rotation with Cain that leaves her questioning the way he operates. Conrad makes a shocking discovery about the hospital.

After being terminated, Conrad has difficulty figuring out his next step and distracts himself by accompanying a patient on a zero-gravity adventure. Cain puts the doctors on a commission-based pay system. Bell's company gets its big break.

When Cain tries to be a hero at a crash scene, he is struck by a car, causing Chastain’s doctors to put aside their personal issues to try and save his life. Conrad and Nic team up to help one of the crash victims, whose secretive past makes it difficult to identify a diagnosis. Meanwhile, Bell brings his TV crew to the hospital in hopes of garnering positive attention for Chastain, and Mina opens up to Nic, only to find out that Nic is holding on to a secret of her own.

While looking for a distraction on Halloween, Conrad treats a group of witches who send the ER into chaos. Also, Devon treats a patient who thinks he is being haunted by ghosts. Meanwhile, on the way back from his vacation, Bell picks up a hitchhiker who is not what he seems to be.