Well the episode is called to Hell and Back (parts 1 and 2). WE don't know for definate who is in danger, but we can narrow it down. Its not Reid because he was the central in "Amplification". It wont be Garcia or JJ. It wont be Hotch because he was the central for last years finale. My best bet is Emily, Rossi or Morgan. I do know it will once again be a cliff hanger and the episode is a 2 hour long special. Hope this helped. :)
Actually I thought that the Reaper might come back again at the Finale. And so, my first thoughts were Hotch or Morgan.
But well, I guess we have to wait til next Wednesday, than we know for sure.
