If you don’t want to read spoilers, stop reading now!
Here’s a quick rundown of what happened:
The group of Carol, Tyreese, Lizzy, Mika, and Judith all came across a nice house on their travels. They stopped in there for a while and got comfortable. They were cooking food on a gas stove and relaxing in nice chairs. Tyreese even confided to Carol that he’s not quite ready to go to a place with a lot of people and would like to settle down in the country house that they found.
Carol found Lizzie playing a deadly game in the yard, letting a walker chase her around while she laughed and had fun. Her peculiar relationship with the walkers got even more strange when she told Carol and the group that she could understand them and that they just wanted her to “change”. After that confrontation, Lizzie’s sister Mika spoke with Carol about the situation and they came to the conclusion that Mika would have to watch after her big sister.
Mika walked up to Lizzy while she was feeding a walker that was trapped in the railroad tracks. They started arguing and some burned walkers came rambing out of the forest in the direction of the two girls. Lizzie and Mika retreated to the house, where they met up with Carol and Tyreese and were able to fend off the small horde of walkers.
The next day, Tyreese and Carol went out to hunt for food. They returned to find Lizzie standing over Mika with a bloody knife. She had killed her little sister in order for her to turn into a walker. She wanted to prove to Carol and Tyreese that the walkers weren’t as deadly as they thought and that they just needed to trust her. She was planning on killing Judith next. Carol played along for now and had a talk with Tyreese about how they should handle the situation.
On the next morning, Carol and Lizzie went for a walk in the woods. Carol told Lizzie to “look at the flowers” as she drew her gun and shot the young girl in the head. Tyreese and Carol then bury the two dead girls near the house.
Afterwards, Carol sat down with Tyreese in the house and confessed that she was the one who killed and burned Karen and David. She placed her gun on the table and told him to do what he had to do. Tyreese forgave Carol for the actions, but did state that he would not forget it.
Carol, Tyreese and Judith left the house the next morning and set their destination as Terminus.