Espionage, for the most part, involves finding a person who knows something or has something that you can induce them secretly to give to you. That almost always involves a betrayal of trust.
“Nothing is going to improve my hearing. I've only got to prevent it from getting worse.”
“We found out the Gemini spacesuit was, well, oxygen was flowing to keep me cool as well as to breathe, and it wasn't good enough. My visor got fogged.”