Peter refuses to sleep, despite Hicks' order, in the middle of a 48-hour shift. His lack of sleep catches up with him when he is supposed to be watching his mother. A doctor, who turns out to be a con artist, visits the ER to use it as a model for a new hospital, in the process offering Susan a job. Jenn tells Mark she wants to separate from him. Dr. Ross treats an abused young girl. Carol receives bad news about her attempt to adopt Tatiana. Morganstern informs Mark he's leaving for Boston and will be strongly recommending Mark to his replacement, leaving a surprised Mark uncertain as to his job prospects.

A busy Dr. Greene goes all day in solving his patients' problems until he encounters the case of a pregnant woman suffering from complications that threaten both her life and her unborn baby's.

Mark, still upset over the loss of Jodi O'Brien, takes the night off but ends up in the ER anyway, albeit an hour late, when the new chief runs a drill at 2:00 a.m. Benton begins to realize his mother's future is not bright. Carter and Deb compete against each other. A small moon coinciding with the naturally heavy Saturday night traffic causes an exciting night.

Deb and Carter compete furiously for procedures after Benton announces their books are due a week earlier than previously announced. Deb commits a nearly deadly error on a patient while trying to keep up with Carter. Doug's relationship with Diane Leeds grows. Peter and Jackie decide to put their mother in a home. Dr. Greene is put on trial, so to speak, in the M conference for Jodi O'Brien. Chloe returns.