On Amy and Sonya's first day as co-chief resident, they must coach a fresh crop of interns through a mysterious case that seems to defy medical logic; Jake and TJ adjust to new roles within the hospital; Dr. Ben Grant returns to Westside.

When a horrific accident sends three members of the same family to Westside in critical condition, the entire staff must band together to save them and avert tragedy. Amidst the chaos, Amy must contend with a flood of emotional memories as …