For three years, Alex has a peaceful, anonymous life in Italy. However, Alex must abandon this idyllic existence when Ryan persuades her to help him rescue Shelby from an international arms dealer, The Widow.
In tracking down the origin of a deadly strain of tuberculosis threatening Americans, Ryan must go undercover and infiltrate a white supremacist organization.
When a physics professor at a major U.S. university steals weaponized uranium, the team scrambles to find the professor and the missing uranium before it can be used against an important international summit meeting in New York City.
The team must protect a scientist who has developed a deadly technology that, in the wrong hands, could have devastating consequences to mankind; Ryan and Shelby stumble on something of Alex's that signals a possible change in her personal life.
Conor Devlin has plans of his own when he plots revenge and returns to his home country, Ireland; meanwhile, the team unknowingly finds themselves as a pawn in his plans.
The team is in Ireland, and when they finally come face-to-face with Conor Devlin, not everyone comes out alive. And Alex makes a life-changing decision about her future.