When Chastain loses all power, Bell is forced to refuse to take patients as the staff struggles to do their jobs without the help of any machines. Tension rises when Connor and Devon defy Bell to help a child.
As the new chairman of the board, Conrad's father draws him into a discussion about hospital expenses. Julian Booth, a representative for a medical device company, arrives at Chastain to promote her company's devices.
When a married couple is admitted with mysterious symptoms, Nic and Conrad join forces to come up with a diagnosis as their proximity to the couple brings up memories about their own relationship.
After a music festival ends on a tragic note, the injured concert-goers end up at Chastain, putting the doctors under pressure as the hospital is flooded with patients.
Kit and AJ find common ground in their disapproval of Bell's decision to use a new medical device company. Julian and Devon grow close.
With Halloween upon them, Devon gets a taste of what working in the ER during Halloween feels like. Conrad tries to help a woman suffering from night terrors find a diagnosis for her condition.
Nic fears for her sister when she realizes that those who have participated in the same drug trial as Jessie have started showing dangerous side effects, prompting her and Conrad to push for the immediate shut down of the trial.
With Bell insistent on using one of the medical devices from Julian's company on Conrad's patient, Conrad clashes with him to get him to reconsider. Mina and AJ's relationship continues to evolve.
As the past comes back to haunt him, Bell considers a risky gambit. Julian discovers an unsettling secret about the medical device company, Quovadis. Devon's nerves start to slip as his wedding day arrives.
When Lane Hunter gets released, she makes Bell's life a living hell as her release on bail garners a backlash. In the wake of his father's health complications, Conrad tries to find solace in a new case related to Lane's past actions.
Hit by a loss that leaves them all reeling, the doctors at Chastain work to figure out if Quovadis' device is responsible and clear the name of one of their own.
With the flu season upon them, the doctors find themselves racing against time to save victims of a horrific infectious disease whose symptoms were mistaken for flu. Mina goes to great lengths to prove that AJ wasn't responsible for Bradley's death.
A risky case sees a number of doctors, including Bell, joining efforts to save the patient, who needs a triple organ transplant. Devon conducts his own investigation into Julian's disappearance after her car is found in a lake.
Conrad's plans for Valentine's day are thwarted when Jessie needs Nic. Mina and Micah hit a snag in their relationship when he surprises her with an unexpected question.
Bell's wavering confidence in Quovadis takes another hit when Henry Barnett gets rushed to the hospital. Mina is forced to confront her past when her mother, a famous surgeon, arrives to help on a case.
With Gordon Page planning to use his devices on veterans, the team at Chastain rushes to find a way to expose Quovadis. A face from Alec's past causes him to question his decision to leave his old practice.
As the life of AJ's mentor hangs in the balance, the doctors face a terrible decision when he and another patient need the same device to survive. Marshall goes to great lengths to guarantee the downfall of Gordon Page.
Marshall pursues new business prospects. The truth about what happened to Julian is revealed. Bell steps in to support Kit when her ex-husband requires surgery. Nic deals with family issues as Jessie returns with their estranged father.
Mina is forced to perform a solo surgery when AJ gets trapped in a blizzard. A professional disagreement between Nic and Conrad bleeds into their relationship. Jessie receives a shocking diagnosis.
Nic and Conrad make a decision about their relationship. Devon tries to help a new mother whose complaints go ignored, putting her life on the line.
With Jessie's health going downhill, Nic struggles to deal with her father's refusal to donate his kidney. AJ receives news about his biological family. Conrad steps in to help a patient whose life is endangered due to a shortage of blood.
Out of options to save Jessie, Nic makes a questionable decision to secure a kidney for her sister. Bell tries every possible way to resolve Chastain's financial problems.
Bell steps in to decide whether to provide or withhold medical care from a John Doe. Nic makes one last appeal to Kyle to save Jessie. A shocking truth is revealed about Chastain's new anesthesiologist.