Conor Devlin plots revenge and returns to his home country of Ireland, as the team unknowingly becomes a pawn in his plans.
The team must work together to protect an ex-CIA agent in order to take down a drug cartel kingpin, a challenging assignment that puts all of their lives in great danger.
When a physics professor at a major US university steals weaponised uranium, the team scramble 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 humankind; Ryan and Shelby stumble on something of Alex's that signals a possible change in her personal life.
Alex and McQuigg are assigned to protect a prince following the assassination of an emir, but the team soon realise the killer is closer than they think.