Susan's last day in the ER finds Mark unsure of himself. Despite Doug's urgings, Mark still finds himself afraid to admit his feelings for her. He chases her all over the city until he finds her at the train station. He declares his love for her, but she decides to leave for Phoenix anyway. Grabarsky and Lydia finally get married. Carol agrees to become "management" in exchange for an end to the policy of floating ER nurses elsewhere. Al Boulet delivers divorce papers to Jeanie. Doyle calls the cops on a pregnant woman who is drunk and trying to kill her unborn baby. Charlie brings a neighbor's baby into the Healthmobile. Carla shows up in the ER and Carter gives her a tour, with Benton in tow.

Rumors sweep the ER when Kerry and Mark cloister themselves to discuss policy regarding HIV-positive employees, prompting Jeanie to publicize her condition. Charlie brings the child she has been caring for into the ER. Doug treats the child and feels obligated to report the child's mother for neglect. Doyle treats an abused woman, and conspires to help her escape her husband. Carter blows off an evening with Gant to spend the night with Keaton. Mark inherits a mangy dog from a patient and decides to give it to Rachel for Christmas, but ends up not doing so when he finds Craig has already given her a puppy. Carol and her mother host a traditional Ukrainian Christmas celebration, to which Doug shows up with Charlie, who needs a favor from Carol. Keaton tells Benton that she won't recommend him for another pediatric surgery rotation.