Before he goes, he’s asked by the CIA to do them “a favor.” They know of him through his Korean Studies professor at X university, Professor Smithson. The Professor consults with the CIA and occasionally identifies promising recruits from his Korean Studies program.
The favor is "simple;" just arrange to meet an unnamed man in the DPRK. The man will have something to tell him. No notes are to be passed, nothing is to be written down or recorded, no questions are to be asked. Kimmelmann is simply to remember what he’s told, it will be "non-technical," and convey it to the CIA man upon his return to the States. The meeting will be facilitated by "helpers" in Pyongyang.
Of course, nothing is really simple in North Korea, and Joseph will be tested in ways he can't even imagine.