Costumed patients create a challenge for the doctors; Derek and Ben work on a new surgical technique; Richard asks a resident to perform his next surgery, angering Bailey.
Ryan goes under cover to stop the distribution of a deadly strain of tuberculosis.
Mario joins Rox and Willis on the scene of a boat crash; Leanne works to save a brother and sister who drank boiling water through a straw as part of a challenge; Max's father tells Leanne to keep Ariel away from his son.
Willis continues to tend to Rox's medical needs; Leanne and Max's father go searching for Ariel; Noa and Mario realize their career choices will mean ending their relationship.
Elliot fears the worst after hearing the testimony by Detective Gomez's wife at his malpractice trial; Rox tries to connect with Willis, but he pushes her away; Leanne attempts to comfort Ariel in the wake of a devastating loss.
