With Kelly and Winnie out of town, Evan drops Nick off at school a bit early. Nick's school friend Krista Lawrence is also around, and Evan also meets Nick's sexy science teacher, Donna Basher. Suddenly, without warning, someone starts shooting! There's a mad gunman loose! Back at the clinic, the others are completely unaware of what has happened. They wonder where Evan is and struggle to take care of all the patients. Sarah helps to deliver a baby for Mr. and Mrs. Simms, a black couple. However, their child turns out to be white and despite Sarah's theory that it may the result of latent genes from old family generations, Mr. Simms suspects his wife of cheating and orders a paternity test. Meanwhile, Evan, Donna and Louis, the janitor, struggle to reach the police. From his secret hiding place, the madman shoots Donna. The police arrive but can't find the shooter anywhere. They suspect he's inside the building but don't dare to enter yet.

Tim brings in three-year-old Zach Field to the hospital. Zach is slowly dying form Canavans and thanks to bureaucracy, the parents have been waiting for him to get treatment for over 1 1/2 years. Suzanne worries when Felicity's behavior shows signs of a compulsive disorder. She goes to Roger with her worries. Zach's only hope for survival is gene therapy but this is still in a trying phase and the board won't go ahead with it. Tim finds out that Roger has a friend on the gene therapy board, Dr. Megan Todd. Tim convinces Megan to give the OK for Zach to get treatment but the board votes her down. Tim the alienates Megan by calling her a coward. Roger snaps at Tim as the hospital has now lost a valuable asset in Megan. Kelly is upset after the shooting at Nick's school. She wants to move far away but Evan doesn't want to leave the practice. Kelly announces she'll take the children and go anyway. Evan promises to fight her on this.