Steven Moffat has revealed the title for Episode 7, the story that will end on the mid-season cliffhanger, is "A Good Man Goes to War."

In other news, the latest issue of Doctor Who Magazine comes in four collectible covers: Amy Pond, The Doctor, River Song, and Rory Williams. The covers proclaim "One of them WILL die in the amazing season opener!" Moffat says: "You see those four different covers for this month’s Doctor Who Magazine? We’re not lying, we’re not cheating. One of those four people is going to die. The Doctor’s darkest hour is coming.

Shows like Doctor Who should have big, colourful, memorable moments that make you go, ‘What the hell -?’ Well this is one of them. If you’re not going ‘What the hell -?’ it’s business as usual, but it’s hard to create a shock in Doctor Who when we’ve already blown up the universe a couple of times! What do you do next? When I came up with this incredible, heart-wrenching twist, I thought, ‘We kill off one of the leads in the season opener! Who’s going to stop watching at that point?’ It lures you in."

However, considering the trailer clearly shows everyone's continued existence beyond the opening episode, if someone does die, I doubt it will be permanently.