In the premiere, a former military doctor deals with a life-threatening situation on his way to work; his ex-girlfriend pursues the night shift's top job; and a clash over business matters unfolds.

TC desperately tries to save his critically injured friend. Meanwhile, Paul tackles a challenging case involving an elderly woman; Kenny helps an injured groom with a secret; and a 9-year-old boy has suspicious injuries.

TC and Paul race to the chaotic scene of an after-dark hog-hunting event that has gone nightmarishly wrong. Meanwhile, a 9-year-old girl arrives for treatment in a case that turns complicated; Drew injures his hand; and Ragosa seeks family counseling.

Injuries at an Alamo reenactment test the staff. Meanwhile, a disoriented patient suffering from amnesia receives care; Drew helps a severely wounded soldier; Topher schedules a vasectomy operation; and Jordan's boyfriend arrives.

A violent storm pummels San Antonio, sending numerous patients to the emergency room. Elsewhere, TC and Dr. Scott Clemmens rush to a mudslide disaster to treat a mother and her son; and Topher braves the storm to help his stranded wife, who's going into labor with twins.

A horrific crash sends dozens of soldiers, including Drew's boyfriend, to the emergency room, where TC and Scott clash. Meanwhile, Topher tries to diagnose a soldier's illness, and Kenny tries to improve Ragosa's online-dating profile.

A shoot-out in the ER leaves Topher seriously wounded. TC tries to control his Afghanistan flashbacks. An explosion at a fertilizer factory sends burn victims to the ER, overwhelming the shorthanded staff. And Jordan discovers a secret about TC.