Paramedic Connor Haus is good at two things--saving lives on the streets of Boston and holding her past against every firefighter she meets. The tragic loss of her partner, Kam, has left her bitter and angry, her work and fellow-EMT Jake O'Harrigan the only pieces of her life she still cares about. Until rookie firefighter Logan Curtis moves to town, and onto Connor's scene, and threatens to rattle the walls Connor has long since put up.