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.

Stunned by new revelations from her past, Emily intensifies her search for the truth. Tensions mount at the FBI as Nick and Julianne race to profile the Federal Annex terrorist.

Reeling from a shocking loss, Emily returns to the FBI to get answers. Meanwhile, Nick and Julianne fear the terrorist may be ramping up for his next attack.

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.

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 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.

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 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.

The FBI closes in on the person who had chosen the victims of the Fentanyl Killer. Emily is once again, confronted by evil touching her family. Nick & Alice try to resolve the problems they have been suffering, but Nick is going to make a horrifying discovery.

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

Emily is serving out the final days of her FBI suspension while struggling to come to terms with the consequences of her actions from the last two seasons. Hyper-vigilant and distrusting of others, Emily sees threats everywhere and takes a closer look at everyone.

Following the deadly events, Emily must race against time to find and save Nick, with the help of his mysterious informant, Kai. Upon tracking his location, Emily realizes there is a more complex conspiracy afoot and is left to grapple with the possibility that Nick has been killed.

Disoriented and drugged into a paralytic state, Nick wakes up in a dark and confined location. Meanwhile, without a body as proof, Emily refuses to accept that Nick is dead and makes a deal to get him back, only to find that Dawkins has laid a trap and everyone is in danger.

Emily’s demand for the FBI to go after Nick is met with resistance, which leads her to set in motion a risky plan that puts her face-to-face with the one man who can lead her to Nick. Meanwhile somewhere in Europe, Nick is being drugged and psychologically tortured, revealing his buried guilt and his insecurities as an FBI agent, a husband, and as a father.

Emily complies with Dawkins requests in order to be taken to Nick, and orchestrates a clever ruse along the way. Meanwhile, as Nick’s guilt and paranoia threaten to overwhelm him, he finally puts a rest to the personal demons that have haunted him.

Nick continues to be tortured but finds an opportunity to try to escape from his captors. Cal and Emily head off to rescue Nick and become closer along the way. When they reach the mysterious location, they find evidence that links to Nick’s case back in Boston, but there’s no sign of Nick.

Emily makes a final attempt to trade the stolen files for Nick and demands proof that he is alive, unaware that Nick has escaped from his captors in a thrilling chase. Nick makes contact with the FBI, and Emily makes a bold decision to confront Cal about his past.

Emily and Nick devise a plan to infiltrate the refugee camp, and Cal poses as a Meridian guard in hopes of finding Armstrong and bringing him to justice. Meanwhile, Crown and Gunnarsen narrow in on Meridian’s mole and an unexpected visitor arrives at the farm.

Nick works to free the refugees and Cal finally confronts Armstrong. When Gunnarsen and Crown go to arrest Deputy Director Webb, they discover something deadly. Meanwhile, Emily tries to get to the bottom of Elliot’s operation and goes to extreme lengths to protect her family.

Emily and Nick are finally reunited with Flynn back in Boston, but the threat of Elliot’s bioweapon still looms large. Emily resorts to drastic measures and make a dangerous choice to ensure her family’s safety.