There's monkey business in the ER as Clemente, Abby and Neela treat an infant chimpanzee. Pratt has a painful failed attempt at reconciliation with his father. Eve promotes Sam, then forces her to be involved as she fires Haleh. Ray discovers Zoe has chlamydia, and is underage. A recovering Dubenko trails the staff via a two-way television hook-up. A boy and his father are injured in a construction accident.

For Neela, what begins as a routine ride-along with Gates and Zadro turns into a defining day when a commercial jet and a private plane crash over Chicago. As Clemente manages the trauma in the ER, Pratt joins Neela on-scene. Luka and Abby wake up together at Luka's, but the crash soon takes them back to work, where the tension between Luka and Clemente continues. As patients flood in, Sam recalls Haleh when extra nurses are needed, and earns Eve's approval. Luka and Abby care for a patient with severe facial injuries while Pratt struggles to save a patient with a heart injury. Ray's youthful friend returns and creates a nuisance. As the day ends, Luka and Abby talk, and awkwardly decide to stay "just friends," while Neela has a welcome, and overdue, visitor.