While hiding from a massive "herd" of walkers, young Sophia Peletier panics and flees into the woods. Rick's failed attempt to secure her sets off a search that dominates the first half of the season.
The episode opens with the survivors fleeing the decimated CDC in Atlanta, aiming for Fort Benning. Their journey is halted by a massive, corpse-filled traffic jam on Interstate 20, which leads to two catastrophic events that define the season's early arc: The Walking Dead Season 2 Episode 1
If you are looking for the version of The Walking Dead Season 2, Episode 1, it is titled "All That Remains". While hiding from a massive "herd" of walkers,