The episode picks up right where episode 5 left off with the phone ringing. Rick is talking to a woman who tells him that she is in a safe place away from zombies. Rick asks her where exactly but she ends the conversation. Later on in the episode Rick gets another call, this time from a male. Rick tells the person that he is with a group of survivors and has a son and a new born and that his wife died. The man asks how she died, but Rick doesn't want to tell him so the man ends the conversation.
Maggie and Glenn go out of the prison to search for more food for the baby.
In Woodbury, the Gov and Andrea are getting closer to one another and end up having sex. The Gov has Merle and a small group hunt down Michonne and kill her in the forest. The group finds a cryptogram made out of zombie parts warning them to stay away that was made by Michonne but they continue to look for her. They end up finding her and a fight breaks out, Michonne kills two of them then some zombies attack her and Merles group. She ends up gutting a zombie as it attacks her and she gets covered in zombie blood. When this happens the other zombies pass by her this is when she realizes that the zombies can be tricked (like in season 1).
Merle ends up killing a person in his group (Phil), he reaches a town and sees Glenn and Maggie. He takes Maggie hostage and orders Glenn to drive to Woodbury. Michonne sees all this happen.
Rick gets another phone call this time from Lori, she tells him that its not his fault and that she loves him and that its time to move on. Meanwhile, Michonne eventually reaches the prison and is met by Rick who had just gone outside in the prison yard after having hallucinations of Lori talking to him on the phone.
As for what happened to Carol. Daryl decides to look for Carol by himself in the prison. He runs into nothing but zombies, and finds one with a knife in its head but its still alive. Daryl notices whoever stabbed it, stabbed it through the cheek and not the brain. He realizes that it was Carol and that it means she no longer has a weapon. Desperate and believing shes dead, he collapses on the ground. He notices a door in front of him that someone was trying to open. He figures it was a zombie trying to get in but failed. At the end of the episode he opens the door and theres Carol laying on the ground, alive but powerless.
About the phone calls. I don't think they plan on using it again. They put that in there as a homage to the comic. But anyways, the three phone calls in order were: Amy, Jim, and Lori