During a hectic last day for Susan at County's ER, Mark struggles with her imminent departure, but still finds himself afraid to admit his true feelings for her. The hospital staff arrange a leaving party for Susan, but it is canceled due to an influx of critical patients from a motoring accident. Susan leaves the hospital unable to say goodbye to Mark, who was busy working on a trauma patient. He manages to arrive just as her train is about to depart (episode 'Union Station). Mark pleads with her to stay because he loves her. But Susan doesn't see a future in Chicago or with him. She kisses him and says "I love you, too" as the train departs.