Season four begins six months after Andy and Nick leave for their undercover operation. We return to 15 Division with them—and quickly realize that everything seems to have changed, but that’s what being a cop is, right? Adapting to new situations, rolling with the punches.... Change is constant, and if you don’t adapt, you’re left behind. So when Andy McNally returns to find that Sam Swarek is now a Detective and that he’s moved on, both professionally and personally, she’s going to have to figure out how to adapt.

Meanwhile, Dov’s life gets awkward when a one-night stand with Frank’s goddaughter becomes more complicated. Chris is torn between staying at 15 Division and moving his new family back to his smaller, safer hometown. Traci is learning to work with new detective, Sam Swarek, while trying to move on from the loss of her fiancé, Jerry Barber and although Nick and Gail are reunited at the beginning of the season, Nick can’t seem to shed the feeling that all is not right between them—a feeling that Gail soon picks up on.

Last season, our officers got what they wanted and had to deal with the repercussions. This year, they will have to look change right in the eye and learn to adapt—leaving them with some big, bold choices to make.[