Jack finds out his ex-girlfriend Meredith needs a venue for a charity fundraiser and has the perfect place: his student Victor’s house. Victor and the other kids are inspired by Jack to party for the first time.

Jack receives an offer from Miles’ publisher to write a book of feel-good philosophy that could be his ticket out of Toledo. Durbin accidentally sets off an emotional firestorm when he reveals that while Stef chose Mary as her emergency contact, Mary chose Michelle.

When Jack is attracted to a student’s mother at a parent-teacher conference, he feigns interest in her son; a group of parents complain to principal Durbin when they notice a piece of controversial student art from Mary’s class.

Jack reluctantly agrees to go out on the town with Mary, Stef, and Michelle; his superiority complex proves difficult for the women to overcome; principal Durbin feels threatened when Helen fills in for him on the school’s morning announcements.

When Jack gets into a petty dispute with the student council president, the situation escalates much too far; Stef sells makeup at school as a side business.

While Principal Durbin struggles with budget cuts, Jack discovers his students pity him – so he rallies, making a splash at the school bake sale and getting kicked out of the bookstore for life.

When Jack leaves his class unattended, a student injury sets off an official investigation and lands Jack in “teacher jail.” An aggressive teacher’s union rep sets her sights on Principal Durbin. The students’ excitement for a substitute teacher are dashed when they find out it’s Helen.

Jack Griffin is a Harvard philosophy scholar who loses out on his dream job and goes to work as a high school Advanced Placement biology teacher in his hometown of Toledo, Ohio. He quickly makes it clear he will not be teaching any biology, however, and, realizing he has a room full of overachieving honor roll students at his disposal, decides instead to use the kids to enact revenge on his rival and take the job that is rightfully his.

An intense cat-and-mouse game begins as Kabir lands up at Danny’s home and the suspicion on Danny gets stronger. Shankar cracks down on Kabir’s moonlighting investigation and orders a shutdown even as Kabir pieces together the puzzle. Danny creates the perfect alibi as he makes a sly attempt on his next target, Nair.

Time is running out for Josh and Danny makes a bold entry into Ria’s world. He also puts his own life at risk in a bid to finish the job with Verma. Kabir struggles to manage both personal and professional fallout as he faces a roadblock that could end his investigation in the organ donors’ deaths. Kabir and Prakash zero-in on a new suspect, Rao and the heat on the case dials-up a notch.

Danny’s killing instincts get sharper as he picks his next target, aspiring actress Anita, and weaves a stealthy bid to entrap her. Kabir faces strong resistance from his new boss, ACP Shankar. Kabir and Prakash crack a vital clue that could prove to be the first link between the deaths of two unrelated organ donors. The duo discovers a startling pattern and a shocking target on the killer’s list.

Danny gets emboldened and selects his second target, the young techie Rahul. When Danny’s best-laid plan goes awry, he makes a desperate and brutal attempt. Kabir’s instinct leads him to begin an investigation into the case. Kabir and Prakash are convinced that there is more to Rahul’s accident than meets the eye.

Danny starts researching on the organ donation process. After tracking down potential organ donors, Danny zeroes in on his first target, Verma and plots an unconventional way to bring Josh one step closer to survival. Kabir refuses to let go of his troubled memories as he and Ria face divorce.

Danny’s world comes crashing down as Josh’s health deteriorates and death becomes a matter of time. An organ transplant is the only hope for Josh’s survival. Danny makes a dangerous commitment to himself and walks down a path of no return. Kabir cracks a nexus between a corrupt cop and a local drug cartel but in doing so exposes himself and his unit to public criticism on social media.

Bell’s confidence in Quovadis continues to waver when the poster child for one of its medical devices, Henry Barnett, is rushed back into the ER, experiencing seizure-like symptoms. Meanwhile, Mina’s past comes to light when her mother, famous Nigerian surgeon Dr. Okeke, pays a visit to Chastain, and Conrad makes a risky move when Henry returns to the hospital.

When Conrad’s attempt to surprise Nic with a lavish Valentine’s Day dinner is foiled, he gives the reservation away to someone who could really use it. Mina and Devon distract themselves from all Valentine’s celebrations by trying to figure out how their seemingly healthy neighbor has suddenly passed away. Meanwhile, Kit gives dating advice to a sex-injured patient, Irving hits a crossroads in his not-so-secret relationship with Nurse Jessica, and Bell decides to celebrate the day in the OR.

Conrad, Kit, Mina and the Raptor work to save the life of a med student in need of a triple-organ transplant, drawing Bell back to the OR for one of the Chastain’s riskiest surgeries yet. After the police find Julian’s empty car in a nearby lake, Devon does some investigating of his own to find out what might have happened. Meanwhile, Mina and the Raptor hound Bell to halt his business with the risky medical device company, Quovadis, and Nic makes a rash decision regarding her sister.

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.

When a medical device fails on a former Chastain employee, an investigation is opened up, which pits Dr. AJ Austin against Quovadis. As Mina and Bell work to get to the bottom of what went wrong, Devon distracts himself with another patient who’s experiencing mysterious stomach pains. Meanwhile, Nic forms a bond with her new partner at the clinic and Conrad’s relationship with the Barnett family and continues to grow.

Lane Hunter’s victims and their families become outraged when she is released from prison. Bell, although responsible for posting Lane’s bail and getting her released, continues to be tortured by her manipulation. Meanwhile, Conrad uses work to cope with the news about his father, and he teams up with Mina, Kit and the Raptor to treat a patient who is suffering as a result of Lane’s dangerous treatments. Then, Devon grows worried when he doesn’t hear from Julian, and Nic sets her sights on a primary physician for their new clinic.

Devon’s doubts about his relationship reach a peak as his friends and family gather for his big wedding day. As Chastain’s leading medical device company, Quovadis, continues to succeed, Julian makes a discovery that leaves her uneasy about her involvement in it all. Meanwhile, Conrad continues to work on his relationship with Marshall and Bell takes a risky offer in order to make a mistake from his past disappear.

Conrad goes head-to-head with Bell after he recommends one of Julian’s risky medical devices to Zoey, who’s already lost one son and is back in the hospital with the other. Nic fears that Conrad may be getting overly attached to his patient. Meanwhile, Mina and Austin grow closer while working on a difficult heart transplant, Devon embarks on a very difficult day and Dr. Lane Hunter returns.

When patients from the hospital’s prescription drug trial start suffering life threatening side effects, Nic fears that her sister Jessie may be in danger. As a result, she and Conrad work to convince Bell that these trials are not worth the risk. Meanwhile, Mina, Austin and Kit must set aside their competitive nature and work together on a patient whose health is quickly deteriorating and Devon uses Julian as the beta tester for a product he’s designed.

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 Bell makes the executive call to utilize Julian Booth’s medical devices, rather than the hospital’s usual products, Kit and AJ must stop their momentary feuding in order to team up against him. Elsewhere in the hospital, Conrad and Nic work to make a child’s dreams come true after finding out his cancer has returned and the rest of the staff takes notice of Julian and Devon’s new friendship.

Chastain is flooded with concert goers when a stampede at a music festival grounds leaves many in need of doctors. As Conrad and Nic race to help Josh Robinson, a professional adventure guide with a long list of prior injuries, Devon works with a musician who swears he is sober, even though his toxicology report suggests otherwise. Meanwhile, Bell stirs the pot when the hospital’s revered orthopedic surgeon, Dr. Kit Voss, demands a better resident, Julian works to get her boss on Bell’s good side and Winthrop continues to push Conrad to believe he’s a changed man.

Nic and Conrad contemplate their past when they team up to diagnose a happy husband and wife who are both admitted to the hospital with mysterious symptoms. Bell and Marshall butt heads on a work trip when their cut-throat business tactics don’t align. Meanwhile, AJ turns down a request from Bell despite Mina’s forewarning, Devon continues to gravitate to medical device rep Julian and the staff gears up for Conrad’s three-year anniversary at Chastain.

Bell grows frustrated when Marshall Winthrop, Conrad’s dad and new chairman of the board, requests Conrad’s input in his discussions about the hospital’s expenses. As Conrad and Nic work to cut costs for their patients in need, Julian Lynn, a sharp and sophisticated medical device rep, meets the staff at Chastain and inserts herself into the ongoing work of the doctors to promote her costly products. Meanwhile, Mina’s relationship with Micah struggles in the wake of his healing process, and Devon is tasked with showing the eager new interns around the hospital.

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.

In a final and drastic attempt to save Nic from Lane’s acts of sabotage, Conrad must call in a favor from the one person he promised he never would. Meanwhile, Mina’s partnership with The Raptor takes on new colors when Micah is rushed back to Chastain with major heart complications and Dr. Bell’s alliance with Lane is put to the ultimate test when one of her patients is readmitted.

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.

Conrad and Devon work tirelessly to save the life of Bradley, a fellow doctor who has fallen through the hospital skylight. As the team contemplates how and why he fell through in the first place, Dr. Bell looks back to when he benched Bradley for falling asleep during surgery. Amidst the madness, Mina is tasked with showing Chastain’s new star cardiothoracic surgeon, Dr. AJ Austin, around the hospital, but is caught off-guard by his volatile personality. Meanwhile, Nic finds renewed enthusiasm when she uncovers an oncologist who used to work with Lane, but while paying him a visit, she fears that she’s being followed.