Credit: AMC

Put on your zombie apocalypse thinking caps — we have a mystery to solve!

There’s a brand new threat coming to The Walking Dead Season 4, which premieres October 13 on AMC. Back when the cast and producers previewed the new season in a behind-the-scenes video, Lauren Cohan (Maggie) teased,  "It's not even the walkers and it's not even other people this time; there's a whole new threat." Comic book writer/executive producer Robert Kirkman said the new threat could be more deadly than the other two combined. New showrunner Scott Gimple added to The Hollywood Reporter, "It's someone we haven't seen before. Someone unusual; you can't stab them in the face, you can't reason with it. It's a force that would be dangerous in this world and in the world of The Walking Dead, it's terrifying.”

What the heck are they talking about? Lauren said it’s not other people, so is the threat an “it” or a “someone” or what? Here are some theories, but please post your own in case your idea is much better!

1. Disease. You could consider whatever caused the dead to rise a disease on its own, but maybe some new kind of disease spreads that turns people crazy or just makes them incredibly sick. Maybe it comes from bugs, like infected bites? That could be scary as hell, especially in a place crawling with critters like Georgia.

2. Natural disaster. Mother Nature is a killer. What if she turns on the group with storms, a flood, or some other unforeseeable event?

3. Something in the water. In the Season 4 extended trailer, Hershel is heard saying, "You step outside, you risk your life. Take a drink of water, you risk your life." Maybe he wasn't referencing a specific water threat, but it would be a serious obstacle for the prison. Could someone poison their water supply?

It's also possible the big new threat is just not having enough food or supplies to feed the 50-odd people who came over from Woodbury. But we know the prison now has its own garden to grow food, and it's not like it's really that new for the group to scavenge for food and supplies. That was one of the reasons for settling at the prison at the start of Season 3, because they were tired of going house to house. So a lack of food/supplies doesn't seem likely as a new threat.

What else? What else? What else? We need more theories, people! Please share, 'cause you might end up being right.

Credit: Celebified Photo: The Walking Dead Villain David Morrissey, Aka The Governor, Books Lead Role In New Amc Pilot, Line Of Sight