Halloween chaos takes over the E.D. Hannah helps a pregnant woman with an autistic son. Charles clashes with nurse Jackie on a psych case.

A familiar face returns to the ED. Ripley and Charles treat a woman with a rare disorder. Frost suspects that his patient's father is lying about his daughter's condition.

Hannah treats a woman whose undiagnosed condition threatens the lives of both her and her unborn child. Goodwin receives a chilling message while battling the hospital higher-ups.

Lenox continues to rankle Archer as the two tackle their new roles; Ripley faces possible suspension over what really happened to Pawel; Goodwin is forced to make layoffs.

When a commuter ship capsizes, the ED finds itself under water as the staff struggles to treat the influx of new patients and deal with bold new employees taking charge.

Ripley and Charles treat a high-risk prisoner who may have dementia. Archer and Sean clash when a resident from Margo's facility lands in the E.D. Crockett receives shocking news.

An infection threatens Marcel's risky liver transplant. Maggie and Charles help a struggling burn unit nurse. Goodwin is forced to make a tough decision about Bert's future.

Ripley struggles to keep Sully's diagnosis a secret when the latter's pregnant girlfriend comes to Med for help. Johnson works to earn a spot in Med's trauma fellowship. Charles and a medical student treat a bipolar artist.

Maggie's budding romance takes flight. After a woman's shocking suicide attempt, Charles searches for answers. Asher works to diagnose a patient who is new to the city and appears with mysterious symptoms.

Ripley and Charles treat members of a cult. Zola's suspension takes an unexpected toll on Crockett. Dr. Abrams' 5-month-old son lands in the E.D. under questionable circumstances.

Archer, Hannah and Charles encounter an expecting father who claims he's telepathic and receiving messages from his yet-to-be born son. Zola works to thaw out a frozen criminal. Ripley treats Liliana's brother as a favor to Charles.

Ripley and Charles treat a patient with obsessive-compulsive disorder. Asher and Archer encounter a woman with a foreign object lodged in her heart. Marcel clashes with the chief of oncology.

Maggie empathizes with a patient whose mother is afraid to consent to her son's risky surgery. Ripley treats someone from his past. Zola questions her instincts after her actions have unexpected consequences.

Goodwin recruits Charles to evaluate her ex-husband's memory. Archer treats one of Sean's peers from the rehab center. Hannah treats a woman from a rural clinic whose miscarriage was improperly treated.

Goodwin is worried after an accident lands two people close to her in the E.D. Archer returns to Med and treats a man worried about a family curse. Maggie and Zola help a patient on a cross-country road trip.

Frustrated with an insurance company, Ahmad takes matters into her own hands, jeopardizing Med's negotiations and Marcel's first day on the board. Charles helps a woman's depressed husband. Asher's first date takes a surprising turn.

A woman from Archer's past returns and threatens his transplant surgery. Marcel clashes with Med's new eager first-year resident. Charles works to repair his relationship with Ripley.

When the E.D. is flooded with patients from a crash, the entire team is pulled in to help. Charles can't shake the feeling that he knows the new E.D. attending. Archer has second thoughts on the eve of his kidney transplant.