Secret Agent X-9

Lloyd Bridges stars as secret agent X-9, in this series that is based on a comic strip. Released in 1945, the action takes place in 1943, during WWII. There's no real secret to this agent, everyone on Shadow Island calls him "X-9," and knows he is an agent for the United States. Shadow Island is neutral, and the Japanese agents are also known. There is one person that is truly undercover, and another that is kept a secret, until the final chapter. X-9 wants whatever the Japanese are after; but doesn't know it's a formula for turning distilled water into aviation fuel. Spoiler alert: X-9 is triumphant, in the end.