Someone in the political Establishment decides to come clean, and you get to interview them
Let's say someone in DC or someone long-affiliated with the federal government is suddenly wracked by guilt. They need to clear their conscience by telling the truth of what they've done, seen, or been complicit in. You're called to interview them, and they'll be 100% honest. Who would you want this person to be, and what would you ask them? Before he died, I would've said George H.W. Bush, because he was (bafflingly) at the center of so much American political malfeasance for decades. I'd want to know about the October Surprise, Iran-Contra, CIA-crack scandal, the Carlyle Group, and Saudi connections before 9/11. I mean, can you imagine how many conspiracy theories he could've affirmed (or laid to rest), saving a lot of people the mental energy in speculating? Anyway, who's someone living who'd be a goldmine?
George W. Bush. The secrets he knows from his dad, the fact that the whole family dynasty is noting short of an internation crime syndicate, how his dad was the second shooter. I'd tell him about the things I saw and the stories people in Iraq shared with me about the horrors of what he did to them...
One caveat, since he's so wracked by guilt, I'd leave an effective implement on the side table next to him...
If I could also request that the subject be magically completely lucid for the complete interview, I'd interview Joe Biden. He's been around forever as a willing puppet of Wall Street.