The FBI's assistant director of national security, Linda Barnes (Kim Rhodes), joins the BAU as they investigate a quadruple homicide of a group of roommates in St. Louis.
When an Army veteran threatens to blow up a pawn shop, Sullivan reflects on his time as a Marine to deescalate the situation; Vic and Dean try to reason with a man battling Alzheimer's disease; Pruitt takes a stand to honor fallen firefighters.
