Emily hits a dead end. Despite this, she follows the remaining shreds of evidence to a wrenching revelation!

Emily learns that Rex was working for someone connected to both her past and her present. Later, Emily is forced to resort to desperate measures.

Emily is forced to deal with another devastating loss. However, her grief soon transforms into drive when she realises Rex Wolfe was only the tip of the iceberg.

Emily and Cal venture off the grid as they track Rex Wolfe deep into lawless territory. Back in the States, Nick struggles to swallow a massive lie.

Emily and Cal travel to Moldova to track down the Fentanyl Killer—a task that proves to be more dangerous than anticipated. Meanwhile, Nick is given an order that challenges his moral code.

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.

Emily and Cal's investigation into the Fentanyl Killer points them toward some dangerous and highly skilled suspects. Elsewhere, Nick's manhunt for the Federal Annex attacker heats up.

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.

Nick and the team try to track down the person who attacked the Federal Annex; a shadow from the past jeopardizes Emily's tenuous balance.

Emily Byrne struggles to make sense of her time in captivity and her tumultuous past. Meanwhile, a deadly terrorist attack rocks the heart of Boston, drawing Special Agent Nick Durand and the FBI onto the case.