The night shift doctors put themselves in harm's way to save the victims of a campus shooting, and TC, Shannon and Drew each make hard choices about their futures at San Antonio Memorial.
While Cain faces new danger from his mysterious past, the night shift crew treats an emergency room full of sick immigrants discovered in a SWAT raid, including one with murderous intentions.
When a cyber attack wreaks havoc on the hospital, TC and Drew must call on their military training to help their patients, and Shannon fights to prove herself after receiving negative feedback.
Drew flashes back to a tragedy from his service days when several veterans seek treatment in the ER, and Paul and Shannon turn to Scott for help treating a Vietnam POW with an unusual diagnosis.
Mac's work with a troubled vet causes a medical crisis for Kenny; Shannon unearths a disturbing secret while treating a young patient; and Jordan helps TC come to terms with Topher's death.