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 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. Old wounds also reopen for Michael when he and Sonya are thrust into a family crisis while trying to save a young addict. Meanwhile, Gina grapples with her life choices when Walter returns to Westside.
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. Despite unease in their relationship, 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.