Patient's exposure to radiation sends the Night Shift into chaos. Topher implements an immediate quarantine and locks down the ER. Paul cares for the quarantined patient with the help of Ragosa and Kenny. Meanwhile, TC, Drew, and Gwen race to the site of a multi-victim car cash, where they discover an injured police officer at the heart of the accident. Back at the hospital TC and Jordan work desperately to save the officer's life using an unconventional procedure. TC gets an unwelcome surprise when his troubled sister-in-law Annie shows up out of the blue. Still adrift and grieving over the death of her husband, Annie is eager to reminisce with TC about the good old days. Meanwhile, a former patient harasses Jordan, and Drew struggles with his recent breakup. Joey pushes Krista to take her future into her own hands.