La Femme Nikita - Season 1 Episode 12 : Innocent 2001

A live nuclear warhead is smuggled into the states and the only witness to the act is a mentally challenged pizza driver named Rudy who witnessed the transfer. A transmission claiming that the warhead is armed in a random city and will detonate in 24 hours is intercepted and Section uses Rudy to determine who the man is that brought the warhead into the country - a traitor in the Agency. The location is discovered and with Rudy's help, Birkoff is able to determine the code that will disarm the bomb in time. Rudy is allowed to live due to his help and is allowed to leave Section with Nikita's assurances that he will never tell anyone of Section or it's whereabouts.