A mysterious, fast-acting and extremely deadly virus triggers an emergency lockdown on the 6th floor of Westside Hospital.

Charlie fights for his life at Westside with Hannah by his side. The Board launches an internal investigation into Brian Clark's resignation, putting everyone in the hot seat. A familiar face returns to Westside.

With the search underway to find out the truth about Amy's hacked accounts, she and Sonya butt heads while treating a homeless patient. Jake and TJ help a distraught mother figure out why her daughter is in a coma. Hannah cares for a charming high school athlete.

The search for Amy's hacker intensifies. Hannah, devastated by the death of her patient, works with Amy to treat a sick man whose daughter believes has been poisoned. Meanwhile, Sonya and TJ examine middle school kids for scoliosis.

Sonya wrestles with treating a guy from her past and must rely on Amy to help her. Richard deals with a family situation. Jake and TJ debate the moral implications of a diagnosis.

Amy and Richard reconnect while treating a patient whose diagnosis is not at all what it seems. A real life romcom comes to Westside Hospital, bringing love to the forefront of everyone's mind.

After a tragic accident, one of Joan's oldest friends is rushed to Minneapolis to be treated by her, forcing Amy to confront her about her illness. Richard and TJ find themselves at odds when they treat a tech bro who thrives on pushing boundaries. Michael tries to pick up the pieces in the wake of his fractured marriage.

The race for Chief resident intensifies as Joan tasks Amy and Sonya with evaluating each other's case work. Amy tends to a politician with a disability. Sonya struggles to find a solution to her combative patient's abdominal pain. Michael's parents come to town.

Amy must confront who she has become after the tragedy that struck her family seven years ago. Sonya and TJ disagree on how to treat a sick Marine, and Amy and Jake make a life-changing discovery about an Alzheimer’s patient.

Amy and Jake treat an expectant mother injured during a robbery. Michael is challenged to open up when Katie's therapist invites him and Amy to a session. TJ and Sonya help Julie navigate a mysterious illness and an unexpected romance.

When Amy and Michael take Katie on a road trip to her college orientation, they pass a familiar campsite and decide to stop and hike the trail. The journey quickly becomes harrowing when they discover an injured man whose life hangs in the balance. Stranded in the middle of nowhere, with no cell service, it's up to the three of them to somehow save him.

When Chief of Internal Medicine Dr. Amy Larsen suffers a catastrophic brain injury, her life is turned upside down. Still determined to once again practice medicine, she charts a new path forward, ready to face whatever obstacles stand in her way.

Amy struggles with memories during treatment of an expectant mother's puzzling illness. Her mentor Dr. Joan Ridley makes a visit to Westside.

A popular weight loss medication reveals the cracks in a couple's relationship and two sisters face an unexpected diagnosis.

On her last day at Westside, Joan chooses an unlikely successor, crowns a Chief Resident and imparts some final wisdom to the next generation. Gina steps in to help TJ's patient, a foster child suffering from rheumatoid arthritis. Amy and Jake's tension intensifies while treating a pregnant teen caught between her divorced parents.

In an effort to save a crashing Richard from a deadly virus, Amy gets infected with it. Michael and the team work tirelessly to help her and the other patients, but their experimental treatments fail, and Amy becomes critically ill.

On Michael's first day as Chief of Internal Medicine, Joan arrives at the hospital as a patient in dire straits. Amy, determined to save her, clashes repeatedly with Richard over Joan's treatment plan. Meanwhile, Gina makes a nearly impossible medical decision for a young patient and Liz fights for her allegations against Richard to be taken seriously.

Amy treats a Chaplain who helps her reconcile with the past, while Michael is under investigation for his actions during the hostage crisis.

Jake refuses to give up on a beloved patient, landing himself in conflict with several Westside surgeons and when Amy's neuro tests elicit memories of Danny, she pushes herself too far.

Amy and Gina, with an assist from Jake, team up to help a victim of domestic abuse, while TJ finds himself in the spotlight when he, Sonya and Liz treat a social media influencer.