Double Agent is the 16th broadcast episode and 12th produced episode of British television series Joe 90.
Joe 90's life is in danger when he is given the brain patterns of a double agent. Instructions are given, "Shoot on sight!"
When three W.I.N. couriers are shot and their despatch cases stolen from them, Shane Weston begins to wonder if there is a traitor in the Courier Department. The situation is now acute because there is a particularly big assignment coming up. New codes and cypher tapes have to be taken to the whole of W.I.N.'s eastern network. It's so important that Harry Sloane, head of the Courier Department, says he will do the job himself, but Shane Weston refuses to allow this. Instead, Harry Sloane's brain patterns are transferred to Joe 90, who sets off on the assignment. Joe's movements are puzzling. When he gets to Paris, he changes 'planes and goes to Copenhagen, and then gives W.I.N.'s men the slip. Now he is in dire danger because it becomes clear that Harry Sloane himself is the double agent, and Joe is acting as if he were Sloane. Copenhagen receives instructions from W.I.N. headquarters to put out a C48 on Joe, it's a red priority to all W.I.N. agents, "Shoot target on sight!" Professor McClaine and Sam Loover have a nightmare chase to try to reach the boy before the instructions can be carried out, but the double-dealing Harry Sloane himself gets to Joe first. In a fight, Joe is disarmed and loses his glasses, which means that he no longer thinks like Harry Sloane. But how are the other agents to know this? When Sloane manages to get away with the case, the situation looks desperate. But there is a remote control "destruct" system in the case which is put into operation. The case explodes and destroys the helicopter carrying Sloane. Joe's life has not been risked in vain, the guilty man has been found and destroyed!