"They aren't learning anything. They're dead, mindless. They walk straight into walls and keep doing it until the wall breaks down or they're shifted in a new direction. The groups happen because they're attracted to sound so they pull towards one another if there's nothing louder, or they all get trapped in a corner. That, or they were all together when they died, which is why the cities aren't safe."

This is all so standard for her that she barely has to think about it; like someone else describing how to put gas in a car or sharpen a pencil.

"The big group I saw was because they all kept getting trapped in a stone quarry and couldn't get back out. We had to break it into smaller groups to deal with so they wouldn't - there was a big truck blocking the exit, so they would have moved it enough to get out eventually and a herd that size would have rolled right over us."

Because no, the communities aren't that big. All they could have done was move out of the way and who knows what that would have meant in the long run, if they even had enough warning to get clear in the first place.

"It's been - it's hard to know exactly, but ten? Twelve years? And yeah they'll thin out over time. But they don't die if they freeze over or get stuck in mud, they just sit there waiting to be turned loose again. They're trapped in mines, and rivers, and houses. Plus we're all infected. Anyone that died as we go turns into one too, and that's fine if you see it, but - we had one man who had a heart attack or something in his sleep. He tore his wife apart asleep next to him because she didn't even know he'd died, got two of the kids before their screaming woke the rest of us up to help.
It's... A mess, still. "