The plot follows a group of highly skilled operatives hired to steal a heavily guarded briefcase. The team includes Sam (Robert De Niro), a former CIA agent; Vincent (Jean Reno), a Frenchman with a dubious past; Gregor (Stellan Skarsgård), a former KGB technician; Spence (Sean Bean), a British weapons expert; and Larry (Skipp Sudduth), an American driver. The operation is orchestrated by Deirdre (Natascha McElhone), who works for an unknown client.

Throughout the mission, the team faces dangerous betrayals and obstacles. The briefcase becomes a symbol of the ever-changing loyalties and secret agendas, leading to intense confrontations and some of the most realistic and legendary car chases in cinematic history, set in Paris and the French countryside.

Ronin delves into themes of trust, honor, and survival in a world of unpredictable allegiances. The cast delivers powerful performances, with Robert De Niro and Jean Reno shining as battle-hardened professionals navigating the murky, morally ambiguous landscape.