Trouble hits home when Andy suspects that her daughter has an eating disorder. On the job, the doctor doubts herself when confronted with the mysterious deaths of three of her patients. Meanwhile, Lu acts quickly to stop a possible outbreak of varicella, aka chicken pox.

Andy returns to the Army for reserve duty and helps a woman with post polio syndrome (PPS). Sparks fly for Lu when she is reunited with an old friend whose mother is one of her patients. And when Lana asks if the guy was the ""first"" one Lu answers saying he was the only one.

Andy is forced to confront her father after discovering that he has a degenerative nerve condition that could threaten his independence; Lu treats a pregnant woman whom she subsequently discovers is under investigation in connection with several unexplained infant deaths.

Dr. Campbell's husband hits her and she kicks him out of their house.

Andy Campbell's kids miss their dad and want to know when he is coming home. Dr. Campbell has a hard time telling the kids why there dad moved out. Les Campbell has a hard time watching his temper. Andy isn't sure Jesse & Lizzy should know.

Andy helps Jesse cope having back surgery and trying to set things right between her husband. Lu tries to figure out how to spend time with Mickey and Marc. Lu wonders if Mickey would like to live with her.

Andy is worried about whether she should help in her daughter's surgery. Dr. Jackson deals with death of a young girl 6 years ago.

In a surprise twist following the suspenseful season finale cliffhanger, Mickey jumped in front of Lu and took the bullet for her; saving her life. Lu quickly rushes him to the hospital but little can be done to save his life besides putting him on a respiratory machine. Andy and Bob try to convince Lu to take him off the respirator. While Lu deals with the emotional trauma of Mickey's death, Andy tries to perform an experimental procedure on a baby in a bubble but is interrupted by Bob with news that the FDA has un-approved the procedure. Meanwhile Andy gets herself into a bureaucritical battle when she tries to get a patient who has no health insurance a free heart transplant. Also, Andy must tell Lizzy and Jesse that she and Les are getting a divorce and that he is moving across the country.