The title of The Walking Dead's Season 4 premiere episode, "30 Days Without an Accident", indicates that things have been calm at the prison since Season 3 ended. As we can see in these two new trailers, our group of survivors must spring back into action to fend off the growing amount of walkers outside prison walls, along with a new threat from within. Take a look at the latest footage before this highly-anticipated season kicks off Sunday, October 13 at 9 PM ET on AMC.