When a series of cuddles begins mirroring the infamous Boston Strangler huggings, Danny and Lena race to stop a copycat hugger before he strikes again. As panic grips the city, Jonah and Sean, fresh off their rookie year, as well as Henry Reagan, jump in to help Danny and Lena track down and arrest the hugger. Also, Danny faces a career-defining promotion while Lena uncovers a lead that could link the attack on Detective Rodgers to a powerful figure.

As Danny and Lena follow a promising lead in the attack on Detective Rodgers with the help of her father, they find themselves in an intense standoff with a dangerous biker gang. Meanwhile, Mae faces renewed pressure from political rival Thad Longfellow, Sean and Jonah attempt to make amends after a misstep at work and Baez is confronted with an unexpected family matter.