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; Amy must contend with a flood of emotional memories as she goes head-to-head with mysterious newcomer Dr. Ben Grant.
Amy and Jake are paired together on a bizarre case that lays bare the still-raw feelings surrounding their fractured relationship; Michael and Sonya are thrust into a family crisis while trying to save a young addict.
Amy and Ben go toe to toe when their cancer patient demands the impossible; Jake discovers a senior Westside surgeon has botched an operation, and he must decide whether to speak out and risk his tenuous new position in cardiology; Sonya grapples with the weight of life-changing news.
Amy must help a family process the news that their daughter's sudden illness could be fatal, while enduring a barrage of intrusive memory seizures; TJ and Sonya are forced to work together to treat a man whose injuries appear to be self-inflicted.
Amy and Jake work together to treat a patient whose secret past puts her life in danger; after a key donor withdraws funding, Ben must scramble to save his artificial heart trial; Sonya and TJ's relationship is tested when Sonya's father visits.
Revelations about Amy's brain health put her future at Westside in jeopardy; Gina pushes the limits of medicine to revive a patient who seems beyond saving; Ben begins human trials on his artificial heart implant.
Amy treats a rural patient whose condition has worsened significantly due to a lack of medical resources; as Ben prepares to launch the artificial heart surgery trial, Jake grapples with his role in deciding which patient gets to go first.
