Owen Davian: We've implanted an explosive charge in your head. Does that sound familiar?
Owen Davian: Who are you? Do you have a wife? A girlfriend? Whoever she is, I'm gonna find her. I'm gonna hurt her. And then I'm going to kill you right in front of her.
Ethan Hunt: You will never get what you want!
Ethan Hunt: I can't get to the roof!
Declan: Where are you?
Ethan Hunt: Look up! Look up!
Luther Stickell: That look in your eyes is pain in my ass, you know that, right?
Answer: It's never explained. This is what's known in the film industry as a McGuffin, a term popularised by Alfred Hitchcock, which is an item that's crucial to the plot, but the exact nature of which is never revealed because it actually doesn't matter in the slightest.
Tailkinker ★