Jeffrey runs afoul of the trustees when a grieving husband has second thoughts after allowing him to test an artificial heart on the body of the man's newly deceased wife; Alan comes to the rescue when a patient's HMO refuses to cover Aaron's operating on her very complicated and potentially fatal brain tumor; Jeffrey visits his wife Laurie, a straitjacketed patient in a mental hospital who apologizes for drowning their son Joey; Arthur's refusal to remove his wagging finger from Jeffrey's face during an argument leaves him with a bitten digit, and enables Jeffrey to diagnose the curable medical condition that's causing Arthur's resting tremor.

Arthur nearly fires Danny for failing to adhere to triage protocol, thereby delaying the treatment of a critically injured prostitute with AIDS; Phillip becomes the acting chief of staff after Hackett suffers a fatal heart attack during a little afternoon delight with Angela in the MRI room; Jeffrey and Arthur argue over the future of a baboon with the potential to prolong the life of Jeffrey's patient with heart failure and Arthur's patient with AIDS.

Jeffrey tells Nadine about Laurie's schizophrenia and the death of his son; Aaron and Camille grieve about their impending divorce; several members of a family of trapeze artists are brought into the hospital in critical condition after a devastating accident during a circus performance; one of Aaron's former patients reveals his bigotry when he refuses to allow Nadine to remove his diseased gall bladder and insists that Aaron or another Jewish surgeon perform the procedure; Jeffrey exhibits signs of a meltdown when, in the space of a few hours, outrageous conduct in a nightclub gets him mistakenly arrested for soliciting a prostitute and he vandalizes the car of a man who stole his parking space; Phillip incorrectly attributes Aaron's angry outburst at one patient minutes after losing another young patient in surgery to tensions with Camille, and threatens to fire Camille if there's a recurrence.

Phillip's religious beliefs and Jeffrey's grief over the death of his son put them on opposite sides of whether to convince a young mother to remove her infant from life support so that her daughter's organs can be donated to save the life of another baby; Karen deflects a flirtation from Jeffrey, but romantic sparks fly between her and Aaron.

Aaron, the staff, and the patients are caught in the crossfire when Antoine Metcalf, a gangbanger and career criminal, follows his latest victim into the E.R. to finish off the job he started, and sprays a room with automatic gunfire before hospital security shoots him down; Karen joins the staff, and successfully teams with Paula to remove hematomas that are preventing Marcus Lavelle from walking, but the trauma of witnessing his mother's being injured in the E.R. shooting leaves the little boy afflicted with hysterical paralysis and still unable to move although the surgery has left him physically fine; reluctantly operating on the shooter, Aaron jokes about how easy and perhaps appropriate it might be to cause Metcalf's death through a surgical hiccup, a remark which comes back to haunt him later when Metcalf dies soon after surgery and his family sues Aaron and the hospital for failure to provide adequate care; Arthur engages in a little ex parte communication to put in a good word

After Karen begins having seizures, Aaron discovers that she is terminally ill from the multiple brain metastases of a melanoma; Jeffrey resents having to perform surgery on a mobster about to enter the witness protection program; when the residents attempt to pull a practical joke on Jeffrey, they unwittingly provide comfort to a dying Karen.

Jeffrey strongly objects when his old nemesis is hired into the plastic surgery department, but they are able to set aside their differences to bring some peace to the mother of a young girl who dies during surgery; a nurse impedes Aaron's plan to allow Karen to die peacefully.

Camille has an innocent and unavoidable mishap in the operating room during a heart transplant on the rabbi who performed her wedding ceremony to Aaron, and blames herself when the rabbi dies later, even though her mishap had nothing to do with his death; an inexperienced new nurse stands up to Arthur; wracked with guilt, Camille reveals the operating room mishap to the rabbi's widow, and only Alan's ingenuity in demanding an autopsy keeps the hospital from a major lawsuit; Aaron and Camille have it out over his lack of emotional support after the rabbi's death, and each of them admit to the hurt caused by their divorce.

Tensions run high as hard truths ring out when Jeffrey, Danny, Camille, Maggie, Aaron, Arthur and Phillip are quarantined in an empty operating room after a possible exposure to Ebola; Jeffrey and Danny perform an emergency bypass after Arthur has a massive heart attack; Aaron and Camille reconcile.