Suppose that a man disappeared twenty years ago and I haven't had a notice about him since then. What should I say to my interlocutor if I want to tell him about this story?
You know, Harry has disappeared.
Though it sounds like he has disappeared recently. Or:
You know, Harry disappeared.
But my opponent could think that Harry had disappeared some time ago and then again had been discovered. Or:
You know, Harry had disappeared.
But here... Why, it's rather strange usage here itself IMHO. That would mean I think that I wanted to tell about some events which had occurred in the past and that Harry had disappeared before those events and had never been discovered until then.
Can anybody throw light upon this matter?