Mission: Impossible (1966) : 1x9

Rollin and Cinnamon go it alone to recover a reel of recording wire containing information on a chemical warfare project aimed at the U.S. The courier carrying it was killed by the enemy, and the wire is missing. The two fake a lovers' reunion and then Rollin slips out during a pre-recorded conversation. To duplicate the circumstances of the courier's demise as closely as possible, Rollin lets himself be discovered and then chased along the same route. He finds the wire, hidden in plain sight as part of a fence. He and Cinnamon plan to recover and smuggle out the wire the same way, but it is taken by a young boy looking for fishing wire. Rollin manages to recover it, and they send the wire out disguised as the wire on a balloon.