Alias, Season 5

Marshall:
It's a subdermal device, placed just below the skull at the brain stem. I've never seen one this small before. Looks like they patched a radio receiver to a powerful microcharge.

[Sydney, Jack and Sloane exchange worried looks.]

Will:
So what - what does that mean?

Marshall:
It means that they - they put a bomb in your head.

Will:
What?!

Marshall:
I know, I know. But there's ... good news. Looks like the charge is small enough that the blast will be localized.

Will:
Wait - wait. So it might not kill me?

Marshall:
No, it'll definitely kill you. There just won't be any collateral damage.