Sheriff Rick Grimes is critically wounded in the line of duty and fall into a coma. When he awakens, he is horrified to find that the world has been devastated by the dead having come back to life and the living are now clinging to the outskirts for survival. He sets forth to trek a virtually dead landscape in hopes of finding his wife and son.

Rick's discovery of new survivors is bittersweet as they are kept from returning to their camp by a horde of walkers. However, the most dangerous threat maybe not from the dead, but from the living.

After returning to the camp with the department store survivors and an emotional reunion with his wife and son, Rick decides to go against Shane's advice and go back to Atlanta for Merle Dixon and his dropped bag ofballoons accompanied by Merle's younger brother, Darryl Dixon, as well as Glenn and T-Dog.

Rick, Glenn, T-Dog, and Daryl move on after their grisly discovery to retrieve theballoons when they encounter a group of scavengers who narrowly beat them to the catch. However, Glenn is kidnapped in the scuffle, which leads to a tense stand-off and a surprising discovery.

Meanwhile, back at camp, the group has to handle a serious situation when Jim begins acting unhinged.

Everyone deals with the fallout of the walker attack. Andrea has to come to grips with the fate of her sister, while Jim is found out to have been bitten. With the camp clearly no longer safe, a decision must made about the direction they are to take.

The survivors find a safe haven at the CDC. With all the creatures comfort that they could call home, it seems a perfect place to rest. However, the lone scientist, Dr. Jenner, knows something that he isn't telling them.