The father of the abused boy that Mark treated last week goes on a shooting rampage throughout the city, looking for anyone connected with the placing of his son in a foster care facility. Mark fears for Elizabeth and baby Ella's safety when Corday doesn't answer her pager. Chen moves one step closer to the chief resident position. Romano fires Legaspi. Weaver confronts Romano, and comes out to him, threatening that she will quit if Kim is not rehired. Carla's husband, Roger, accuses Benton of sleeping with Carla. Cleo cuts her hand while treating an HIV-positive patient. Luka draws unhappiness from Abby when he sends in her med school reapplication without her consent. Carter expresses his feelings to Abby and begins thinking about his future at another hospital. While treating the shooter alone in an elevator, Mark makes a critical decision regarding his care when the man flatlines.