@UchLove
Okay... First off? Congratulations on wanting to write a screenplay. I mean that sincerely. Save the Cat seems to do that to a lot of people. Second? It's a LOGLINE and not a longline or a long line. Let's get the terminology straight so we're all on the same page. Third?
@indietalk and
@directorik are both correct... There would be no representatives of the FBI in North Korea let alone a spy. The FBI does go undercover but only here in the United States. They do have people stationed overseas but those agents are in the FBI's Legal Attaché program. They basically work with local law enforcement when an investigation would be of interest to our country (U.S.A.). The FBI does have a Legal Attaché in Seoul, South Korea so maybe that's your IN if you want to keep the whole idea of the FBI being involved.
Before you write a spec screenplay, it's PRUDENT to go ahead and create a logline beforehand and then memorize the hell out of it and maybe even print it out and keep it with you and even post it in front of you as you're writing... Especially when you're a new screenwriter. Why? To help keep you ON TRACK while you write. I call this a COMPASS LOGLINE i.e., it's NOT a marketing logline to help sell the final draft of your script but a logline that keeps pointing you toward the actual CONCEPT of your story so you keep on track as much as possible during the writing.
Once you get a final draft completed? Then you can and SHOULD sit down and come up with a MARKETING LOGLINE that is going to get people INTERESTED in your spec.
The two loglines are completely different but once your spec is completed, you can cannibalize your compass logline a bit to craft your marketing logline.
Right now, based on what I've read? You don't yet have a story... YET. Which is fine. You have an IDEA and now you have to figure how to expand that idea into a story. I think involving an FBI Legal Attaché could be a great story. Maybe something happens in Seoul that leads the Attaché to North Korea but if that's what you make happen, know up front that the FBI agent/attaché is going into North Korea ALONE and would be going rogue so to speak do whatever he has to do there. Which in and of itself ain't such a bad idea.
At this point, I think you need to perform some research so you can brainstorm this idea even even more so you can expand it into an actual concept and story.
Like for now? Who's your Antagonist? How does the FBI agent get involved with the North Korean? What incident LED up to all this taking place?
You've just got some missing parts that really need to be filled in before we can help you. Get those missing parts figured out and keep this thread OPEN and we can go from there. I think it could be a great thread for others to keep up with.
GOOD LUCK WITH IT!