It's been a decade since the group of zombie apocalypse survivors led by Rick Grimes (Andrew Lincoln) reached the Center for Disease Control in "Wildfire," the penultimate episode of The Walking Dead's first season. In the episode that premiered on November 28, 2010, the Atlanta survivors decide to head to the CDC after they discover Jim (Andrew Rothenberg) is hiding a bite that he sustained when walkers descended on the camp an episode earlier in "Vatos." As a feverish Jim worsens and tensions rise between Rick and best friend Shane (Jon Bernthal), Rick radios Morgan Jones (Lennie James) to urge him and his son to follow them to the CDC.
When Morales (Juan Gabriel Pareja) tells Rick his family of four are leaving for Birmingham, Alabama, he parts ways with the Atlanta camp. (It would be his last appearance until season 8 episode "The Damned," where Morales captures Rick at gunpoint as a member of the enemy Saviors.)
After Jim becomes delirious with pain and convinces the caravan to leave him behind, CDC virologist Dr. Edwin Jenner (Noah Emmerich) speaks into a video camera. Jenner reports it's been 194 days since the declaration of "Wildfire" and 63 days since the virus of unknown origins went global.
Jenner considers suicide when he accidentally destroys invaluable TS-19 samples of flesh that have not yet become entirely necrotic, and Rick's group begins to panic when they find the outside of the CDC is a warzone littered with rotting corpses. Daryl (Norman Reedus) tears into Rick for leading them to a dead-end and Shane pushes the group to make the 125-mile trip to Fort Benning, but Rick spots a moving security camera indicating someone is inside the locked-down building.
A desperate Rick pleads for the watcher to open the doors, telling whoever-it-is "you're killing us," but he's ripped away by Shane just as the survivors are bathed in white light from the freshly opened doors of the CDC.
After "Wildfire," The Walking Dead creator and executive producer Robert Kirkman explained why the show visited the CDC when Jenner and the facility didn't appear in the comic book, where the survivors are never privy to the science or the origin of the virus that causes the freshly dead to reanimate as walkers.0comments
"It occurred to me that, if this were to happen to real people, then real people wouldn't be concerned with why it's happening and how to fix it. They would just be concerned with finding food and surviving from day to day," Kirkman told Entertainment Weekly in a 2010 interview. "But [then-showrunner] Frank Darabont said, 'We're in Atlanta and the CDC is based in Atlanta. Why wouldn't they at least pop by?'"