Three years after Alex left her old life behind, she is drawn back into the line of fire after Ryan appeals to her for help to rescue Shelby from an international arms dealer.
With the US under threat by a bioweapon, Ryan goes undercover in an attempt to gather more intel, a mission that puts his life on the line but gains the team a new member.
When the team is assigned as a protection detail to a former CIA agent, they fight to get him alive to court where he is set to testify against a cartel kingpin. But the CIA agent turns out to have a hidden agenda.
Acting on a tip, the team splits up to protect an Arabic prince from an assassination attempt and uncover the identity of the would-be culprit.
The team races against time to locate a professor who has stolen weaponized uranium. The stakes are extremely high as they identify his likely target as an international summit being held in New York.
The continued investigation into the Widow reveals Jocelyn's traumatic undercover experience. As the team races to rescue a face from Jocelyn's past, members of the team end up being pitted against each other.
As the team deals with Celine's death, they are assigned to protect a number of scientists and their dangerous technology from falling into the wrong hands. But the scientists' rash decisions complicate the mission.
Alex's newest assignment forces her to go undercover to investigate a military contractor. But the mission goes awry and takes a terrible toll on Alex.
An old acquaintance of Shelby's enlists her help, forcing her to reckon with a past mistake as the team rallies around to protect her and her former asset.
When two of their own suffer devastating losses, the team comes to realize that someone is taking out their loved ones.
Harry's sister is kidnapped to be used against him. Delvin concocts a plan to get himself extradited to Ireland, pulling the team's strings and turning on his own ally in the process.
The team races to rescue Harry's sister despite some hiccups in their mission. Delvin plots his revenge.
With Delvin preparing for his final play against the team, Ryan is forced to make a difficult decision to save someone dear to Alex.