A briefcase with undisclosed contents – sought by Irish terrorists and the Russian mob – makes its way into criminals' hands. An Irish liaison assembles a squad of mercenaries, or 'ronin', and gives them the thorny task of recovering the case.
An ugly duckling having undergone a remarkable change, still harbors feelings for her crush: a carefree playboy, but not before his business-focused brother has something to say about it.
When Ethan Hunt, the leader of a crack espionage team whose perilous operation has gone awry with no explanation, discovers that a mole has penetrated the CIA, he's surprised to learn that he's the No. 1 suspect. To clear his name, Hunt now must ferret out the real double agent and, in the process, even the score.