Lily Goff

An ever present butterfly prompts the question on what could have happened different as Turk looks for his lucky do-rag for surgery, and Elliot tries to find a lost stuffed animal for a child needing a bone marrow transplant.

A 2004 case involving the disappearance of a female Iraqi war veteran, Dana Tucker, is reopened when her prosthetic arm is found in a river. When Dana returned from the war, she was not the same. She returned home as a hero to the community -- but not to her fellow soldier's widow, who is the prime suspect in Dana's disappearance.

In the season premiere, it's the first day of fourth grade for Ritchie. When Christine and the other moms meet the class' disarmingly handsome new teacher, Daniel Harris (recurring guest star Blair Underwood), they decide to schedule a few parent-teacher conferences immediately. Meanwhile, no longer dating New Christine, Richard stays with Christine while he builds a new laundry room for her. But problems arise when Ritchie misinterprets the comfortable arrangement and believes his parents have gotten back together. Christine scrambles to find a way to explain that she could never reunite with Richard--or could she?

Concerned about the uniformity of Ritchie's schoolmates, Christine takes it upon herself to help diversify the student body at his exclusive private school. But her attempt to promote racial and ethnic diversity has unintended consequences. Recurring guest star Wanda Sykes appears as Christine's friend Barb.

Christine feels pressured to throw an extravagant party for Ritchie's ninth birthday, his first involving children from his new private school. Christine decides to have an arts-and-crafts party at her home--with mixed results.