In the Season 4 finale, a shooting at a nearby college sends TC, Jordan, Drew and Amira into the field, where they assist Rick with a deadly situation. Scott implements a new training program and locks horns with Julian. Drew struggles with frustrations about going to Army Ranger School while Shannon and TC both contemplate their future at San Antonio Memorial.
TC and Jordan accompany a SWAT team on a raid and wind up with an emergency room full of sickened immigrants, including one with murderous intentions; and Scott pulls a dream team together to impress the Colonel in charge of setting up a combat training program. In other events, more is learned about Cain's past; Kenny shares some big news with the group; and Shannon keeps something personal from Paul.
A cyber attack creates chaos in the hospital. Meanwhile, Drew draws on his medical and military training to treat a critical patient, and TC joins on a SWAT drug raid. Also: TC contemplates returning to Syria to tie up loose ends.
Multiple veterans are injured and brought to the hospital. Also, a politician from Drew's past triggers flashbacks to his time in Iraq; Paul and Shannon must improvise while tending to a former POW; and a fearless photographer is treated.
Kenny joins Drew at his MMA veteran's support group and finds himself in the fight of his life. Jordan and Cain treat casualties from a hotel fire, while Shannon follows a hunch to help save a young victim. Paul's superstar sister, Dr. Bella Cummings, pays a visit to San Antonio Memorial and provides desperately needed support during a busy shift. Meanwhile, TC finally returns home, forcing him to deal with Topher's death.
Drew faces an emergency on his flight home when passengers become sickened. Also, some staffers participate in an obstacle-course fund-raiser hosted by Akbar Gbajabiamila ("American Ninja Warrior"); Scott has an unforgettable date; TC treats a soldier.
A patient from a distant town arrives for surgery. Meanwhile, Jordan gets creative to help a veteran in need; Drew struggles with being a working parent; Kenny learns to not worry about trivial matters; and TC joins in a daring rescue mission in Syria.
Jordan and Cain travel to the scene of an oil-field explosion and treat a patient with extreme injuries. Also, Drew and Paul try to save a patient's severed hand; Scott encounters a person from his past; and TC tries to help a sick Syrian child.
An amusement-park disaster results in mass-casualty victims flooding the hospital. Also, TC continues his quest to reunite with Syd; Drew reevaluates his priorities as a new father; Jordan tries to get Paul back on staff; Scott pursues a more active role in the hospital.
Jordan and Drew perform a daring rescue in the Season 4 opener. Also: Paul deals with fallout from standing up to his father; Scott dives into his professional life; a traveling nurse with a mysterious past arrives; and TC is held captive in Syria.