When AMC informed me they weren't going to give me the advance screener for this episode, I knew at least one character was going to die. That's usually how it goes.

Sadly, we had two tonight.

This was one of the toughest episodes emotionally in awhile because we lost the two girls Mike and Lizzie.

This was yet another hour focused just on one group of survivors. We get to hang out with Judith, Carol, Tyreese and the two sisters.

We knew before this episode that Lizzie was a problem child. She had trouble understanding what the zombies are. She didn't see them as killers. She saw them as pets. She fed them rats at the prison. Even her younger sister Mika knew she had psychological issues.

But she's even crazier than we could imagine.

Early on, Carol has a heart to heart with Lizzie, who finds out Carol had a daughter who died, partly because she was too sweet. Carol then talks to Mika, who says she doesn't feel a desire to kill. "I don't have to be tough. I can run. I'm good at that," Mika says brightly.

"My daughter ran. That wasn't good enough,' Carol says. Mika says she's not like her sister. She's not "messed up. I know what they are. I can't kill people... Killing people is wrong."

She realizes that Mika is like Sophia. Unless she toughens up, she won't be long for this world. "Sooner or later, you'll have to do it or you'll die," Carol counsels. "Change the way you think. Everyone does now."

Carol, who began this show as a meek, battered wife, is now one of the toughest characters on the show. She has changed.  She's had to.

The five survivors find a farm and a pecan grove. It's lovely. Tyreese at first thinks it's a good place to stay instead of seeking Terminus, the supposed sanctuary. He is still mourning the death of his girlfriend Karen and isn't ready to see other people anyway. The lack of knowing who killed her was still eating at him but he is happy to be in a house for a change.

While Carol and Tyreese are checking out the house for walkers, Lizzie and Mika argue over whether walkers are people. A walker suddenly exits the home and tumbles over the rail, in position to attack Lizzie, who is holding Judith. Mika shoots the walker, saving her sister. Impressive! Carol is happy.

But Lizzie is oddly upset that the zombie "died."

Later, we find Lizzie feeding a rat to a zombie that can't move. Mika tells her how psycho that is. Lizzie is even ready to have the walker bite her.

But some crispy burned out zombies who emerge from a distant fire arrive. The kids scream. The foursome proceed to shoot the zombies. Carol is again happy because Lizzie was able to kill walkers when need be. Maybe she "gets" it after all.

Carol's hopes of normalcy are short-lived. Lizzie is soon seen playing around with a walker as if it's a pet, not a deadly being. Carol has to kill it. Lizzie is again upset.

She also feels guilt when Tyreese talks about dreaming of Karen, who Carol killed many episodes ago and led to her banishment by Rick. You think she's about to confess but she doesn't. Instead, he ends up comforting Carol. "Don't be ashamed of what you are," he says. "You did right by these girls. You did right by everyone." She's not so sure.

Then the mind-blowing shocker: Lizzie kills Mika. Better yet - not in the brain! Why? Just so she can prove that Mika can come back and be like these other walkers. Same, yet different. She even points a gun at Carol! Carol and Tyreese don't panic. Carol convinces Lizzie to give up the gun. Tyreese leads Lizzie away. Carol collapses in tears. She has to do the dirty work and knife Mika in the brain, which we fortunately don't have to see.

Soon after, she and Tyreese agree without saying it explicitly: Lizzie has to go. And no, not go into time out or a psych ward because psych wards don't exist in the zombie apocalypse.

Carol pretends to lead Lizzie back to Mika. Whenever Lizzie has needed comfort, Mika has told her to look at the flowers. That's what Carol did in the grove before she shot Lizzie in the head. Her death at this point was inevitable and necessary. She wasn't someone you could trust to be around if she could kill her sister like that. Carol had to make yet another tough decision.

But her guilt is so heavy now she confesses to Tyreese and hands him her gun. "Do what you have to do," she says, with resignation and acceptance of her fate.

Tyreese tenses up, has his hand around the gun. But he softens up. He says he forgives her, but he won't forget. He knows that Carol felt she had to do what she had to do with Karen to help save the group at large. He doesn't have to like it but he understands her reasoning and they go off together, away from the grove. He no longer wants to stay.The good news for Tyreese is he has closure. He now knows who killed Karen.

Carol is relieved that Tyreese forgives her.

Now they are on to Terminus.

In essence, neither Mika nor Lizzie were suited for the zombie apocalypse world for very different reasons. As some folks on Twitter noted, Carol had to put Lizzie down like Old Yeller. She was sick and fated for death anyway.

Two more episodes ago. Let's get to Terminus!

Zombie death count: Eight. Mika killed one to save Judith and Lizzie. Later, Tyreese, Carol, Mika and Lizzie kills off six crispy burned walkers. Carol also kills another walker Lizzie was "playing" with. We never see Mike "turn" because Carol killed her before she had the chance. And Lizzie was shot in the head. Immediate death.

Ratings: Viewership was flat at 12.6 million viewers from a week earlier.