Camille serves Aaron with divorce papers; Phillip benches Arthur from further surgery when Arthur's resting tremor begins to endanger patients; Aaron removes a brain tumor from an elderly patient; Jeffrey and Aaron separate conjoined twins.

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.