In the series' 150th episode, a massive train wreck mobilizes the emergency room doctors. Corday, Carter and Kovac rush to the scene. Corday falls and injures her back, bringing on contractions in only her 25th week of pregnancy. While amputating the legs of a fallen firefighter, Corday stops because of her pain.

Weaver fears for her own reputation when Legaspi is accused of sexual harassment. Afraid to reveal her relationship with Legaspi--for both personal and professional reasons--Weaver fails to support her during the investigation. An infant is abducted from the hospital and later found on a train platform.

A demented patient causes a shootout in the emergency room. After terrorizing people in the ER with a gun, she gets shot by a policeman. She soon dies. Benton later discover her dementia was caused by an aftereffect of his surgery that he and Cleo should have detected. Carter pursues a cute intern.

Numerous mishaps threaten to mar Corday and Greene's wedding day. As the very pregnant Corday becomes increasingly agitated, the presence of her bickering divorced parents does little to improve her mood. With the intense rain, Greene has a difficult time making it to the church. But, evenutally, he arrives and they joyfully wed.

Abby and Carter travel to Oklahoma to rescue Abby's mentally ill mother and bring her back to Chicago. In Chicago, Maggie suffers from a sleeping pills overdose. At County General, Kovac frantically revives her. Benton treats a college student injured in a fraternity prank.