As a patrol officer, Jenn Penton is constantly facing new challenges - with every traffic stop, every call, every assignment. She's called upon to solve problem after problem, day after day, and is one of the department's best. But her family has shown her that life doesn't always present issues that can be solved in short order. Her twin sister Melissa has been battling addiction problems for years, and after a few recent setbacks, has reached back out to Jenn - maybe for the last time - for help. On the fugitive unit, meanwhile, Winston DeLeon and company are pursuing a suspect from a rape case dating back to 1992. DNA testing matched the guy back to the crime, and now the Boston Police has to find him. And Manny Canuto and D Araujo of the gang unit find themselves assisting in another SWAT raid, continuing their unrelenting quest to get as many guns off the streets as possible.