Answer:
You don't have to do anything, just have to go and try to save that spy.
Step-by-step explanation:
Look, if we pay attention at the details, we will get to know that the spy is illeterate. And if he is illeterate, that means he can't write normal language, but if he can't write normal language, then how can he even write coded spy words? Now, that was a really good detective riddle.
Thanks! Hope I made your day just a little bit better!