Continuing through the season. Question. At the end of the Kansas City episode why did the Clickers attack out of the ground and then retreat at the end?

This was kind of cool. TNT was watching the special features (thank you optical discs) for the Kansas City episode and the young actor who played Sam was actually deaf. Much of the cast and crew tried to learn some some language while he was onset and they said he was happy to teach anyone who wanted to learn. Pretty awesome.