2. The CDC
The second to last episode of the first season saw the group leave their camp site having just tied Jim to a tree, knowing he will turn after being bitten. Where will the gang go in the rest of the episode? After a quick commercial break we get to meet Dr Jenner, talking away to his exposition-cam about how he cant sleep at night. We see him walk around a medical facility with music playing and electricity running fine as well as a few more of the luxuries our main cast members have been deprived of. All the while fans, not just of the comics, were asking Who the hell is this guy and what is going on? Rick and the group find Jenner at the CDC which is a secure building that can accommodate them. Perhaps not forever, but certainly better than the campsite they just left. The only problem being that Jenner wants to destroy the CDC and spare everyone a harsh, painful death from fighting the zombies by providing a quick, fiery one with him. This event was nowhere to be seen in the books, likely because the comics obviously always operated with a much longer timeframe. The first season only had six episodes so the CDC probably created to give the season an ending event. Jenner, however, ends up giving everyone an opportunity to leave
only after the countdown is started and the gang (those who wanted to keep living, anyway) get to escape. So what was Jenners point? Either kill all of them, or simply kill yourself and leave the people who wanted to survive a huge, supply filled building.