When a wedding crasher is murdered, a runaway bride is the prime suspect; Danny makes a decision about his relationship with Gabby.

Greene returns from his mother's funeral and argues with Weaver over the wishes of a dying patient. Corday receives a big promotion, and Elaine becomes furious when Carter discovers her secret.

A truck crashes into a coffee bar moments after six-months pregnant Carol Hathaway leaves it, and at Chicago's County General Hospital the staff treat the accident victims.

Weaver introduces Greene to Dr Gabriel Lawrence, a physician reputed to be a founding father of emergency medicine, but Greene immediately dislikes him, and they argue about ordering a test for a patient.

A prank in a high school science class goes terribly awry, injuring a teacher and several students. Meanwhile, Hathaway discovers Meg's drug addiction, and Weaver and Greene notice Lawrence gets easily confused.

Lawrence's career is in jeopardy, while Hathaway resolves to handle Meg's drug addiction, and Benton takes a paternity test to determine if Reese is his son.

Lawrence's problems become noticeable, and his memory begins to slip, but Carter has other matters on his mind. Elsewhere, Cleo fails to diagnose an iron overdose after a young girl takes too many vitamins - with fatal consequences.

Benson and Stabler investigate the murder of a top lawyer, and soon discover the victim also worked as a stripper. In the meantime, DNA evidence turns their attentions to her boss's husband.

Charlotte is determined to get Lucifer to leave Earth by turning Chloe against him. Meanwhile, Amenadiel has begun working as Charlotte’s soldier, causing Maze to question his loyalty.

Lucifer and Chloe suspect that a restaurateur's son played a part in the restaurateur's death, while the return of Chloe's mother sends her life into upheaval.