Emily's investigation into her past becomes a hunt for a serial killer whose crimes have been overlooked in the citywide chaos. When the serial killer claims a victim close to Emily, she returns to the FBI to hunt him down, partnering with Special Agent Cal Isaac a former Navy SEAL with a personality that runs counter to Emily's.

While investigating the home of the most recent Fentanyl Killer victim, Emily obtains a critical piece of evidence. Meanwhile, Nick's work with a high-profile prisoner turns deadly.