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. Time is running out and Evan has to use some v