Chastain is flooded with concert goers when a stampede at a music festival grounds leaves many in need of doctors. As Conrad and Nic race to help Josh Robinson, a professional adventure guide with a long list of prior injuries, Devon works with a musician who swears he is sober, even though his toxicology report suggests otherwise. Meanwhile, Bell stirs the pot when the hospital's revered orthopedic surgeon, Dr. Kit Voss, demands a better resident, Julian works to get her boss on Bell's good side and Winthrop continues to push Conrad to believe he's a changed man.

Halloween at Chastain proves to be just as spooky as ever when Conrad is tasked with diagnosing a young woman admitted to the hospital with extreme night terrors. Meanwhile, Devon faces his first Halloween in the ER, Nic panics over her decision to bring her newly sober sister to Mina's epic annual Halloween party and Bell finds an interesting way to make use of his new assistant.

Conrad comes under fire when a former patient files a malpractice lawsuit against him, putting Bell in a difficult position with Red Rock. The doctors perform a risky brain surgery. Mina discovers that Adaku has a dangerous heart condition.

An attack by cyber criminals sends the Chastain ER into a tailspin and Kit tries to figure out whether or not to pay the ransom. The Raptor deals with a personal connection to the patients brought into the ER during the attack, leaving them all vulnerable. Meanwhile, Conrad works on balancing life as a new dad and Devon and Leela debate taking the next step in their relationship.