A doctor reporting a crime sees Brander bring in a foreign criminal with a very suspicious disease, which she thinks might be Ebola. Instantly Police headquarters is put in quarantine. Without being able to get out, Mannion has to count on Ella, who was at home preparing for her wedding, to keep the order while he breaks through Brander's isolation bubble to save his life. Meanwhile, Debreno drives in the snow to find a delirious Temple, who was exposed to the bacteria and might be contaminated with what was later discovered to be a harmless African flu. The next day they all attend Ella's wedding, where Ricky calls her "mom" for the first time.

Debreno is assigned to protect a country singer, scheduled to sing at the Kennedy Center Honors, who's receiving death threats. Elsewhere, to lead by example, Mannion hits the streets as a uniformed cop to make quality-of-life arrests on charges such as disorderly conduct, gambling, and prostitution. But one of his arrests sparks a chain of events that leads to the reopening of a cold-case murder.