Matt Weston (Ryan Reynolds) is a junior CIA agent, drafted as housekeeper at a CIA safe house in Cape Town. Frustrated with the tedium of his placement and hiding his top secret career from his girlfriend, Ana Moreau (Nora Arnezeder), he hassles his mentor, David Barlow (Brendan Gleeson) for the chance to prove himself.
When ex-CIA agent turned international criminal Tobin Frost (Denzel Washington), acquires a micro drive of top secret files from a rogue MI6 agent, a mysterious group led by Vargas (Fares Fares) attempts to assassinate him. A chase ensues through the streets of Cape Town, but as Vargas men close in, Frost turns himself in to the US consulate to avoid capture.
When Frost is brought to the safe house by Daniel Kiefer (Robert Patrick) and his men, Vargas men storm the place, leaving Weston as the only surviving agent. Weston escapes with handcuffed Frost, and takes him to a temporary location while he awaits instruction from HQ and contacts Ana, telling her to leave her house, for fear of her safety.
Barlow's pugnacious counterpart, Catherine Linklater (Vera Farmiga) orders Weston to collect a bag and GPS from a locker at Cape Town Stadium, giving the location of another safe house. Frost creates a scene to alert and deceive stadium security, who separate and detain the two. When Frost escapes security and acquires a guards uniform, Weston soon follows, but fails to capture Frost after a stand-off with the confused stadium security, in which Weston shoots a guard.
Frost takes advantage of the distraction by ambushing Weston. Frost disarms and pistol whips Weston but spares his life saying he "only kills professionals".
Having lost Frost, Weston is ordered to stand down. He visits Ana, as she is boarding a train to continue her life in Paris, and confesses all about his secret life as an agent. Weston's orders are to go to the US consulate in Cape Town for debriefing. Barlow and Linklater are ordered to go to SA to find Frost.
Against orders, Weston tracks down Frost at a nearby township using a CIA database from an Internet cafe. His use of the CIA database alerts the CIA situation room.
Frost is acquiring fake documents from an old friend. Vargas' men attack the shanty house but Frost manages to escape on the rooftops although the forger and his family are all killed. Weston manages to catch up and rescues Frost. Suddenly they are t-boned by another vehicle. They enter an abandoned building and Frost and Weston manage to kill three pursuers. Weston discovers they are working for the CIA, Frost is wounded. They break into a drugstore to bandage up and discuss the situation.
Landing in their private jet and en route to the new safe house, Linklater alerts Barlow that she thinks Weston has gone rogue. When Linklater mentions a microchip with confidential information about various intelligence agencies possibly in Frost's possession, Barlow shoots her and leaves her by the roadside, revealing that all is not as it appeared.
Weston takes Frost to another remote safe house occupied by another housekeeper as planned initially. Once Frost is handcuffed in one of the rooms, the housekeeper attacks Weston, but Weston overpowers and kills him after a bloody fight throughout the house. Badly beaten and suffering a heavy stab wound to his side, Weston manages to free Frost, but then collapses, only to wake up in a bed, with Barlow and Vargas at his bedside and Frost gone.
Barlow interrogates Weston about the leaked files, revealing to him that the files were put together by Israel Mossad to blackmail western intelligence, he admits he is incriminated. Frost suddenly returns and ambushes the safe house and kills Vargas, but is shot by Barlow. Weston grabs a gun and kills Barlow. Frost collapses and as he is dying from the gunshot wound, hands the incriminating chip over to Weston.
After recovering in hospital, Weston is debriefed by CIA Director Harlan Whitford (Sam Shepard), who asks about the leaked files. Weston denies all knowledge of the files, but on his departure, wikileaks the file from his blackberry, exposing the corruption at the CIA, MI6 and other agencies.
In the final scene, Ana is sitting at a café in Paris, where Weston sends her a note. Ana looks up to see Weston across the street.