Every time someone asks you to “look at the flowers” from now on, be very, very afraid.

The Walking Dead went where few shows are willing to go last night. It did something extraordinarily brutal and morbid, even for a show that‘s built an empire on being brutal and morbid. Let’s just get it out there now: Carol killed a child. She shot her at point-blank range in the back of the head while out looking at flowers. Earlier in the episode, that child stabbed her own sister to death to prove a point. That’s “The Grove” in a nutshell.

The deaths of Lizzie (Brighton Sharbino) and Mika (Kyla Kennedy) weren’t shocking in and of themselves. We all knew two little kids—one who can’t even bring herself to hunt deer and the other a budding psychopath—would never survive. And with Terminus on the horizon, Carol and Tyreese will have bigger things going on than babysitting (except for Judith, the planet’s most durable baby).

But nobody could predict the way this would play out.

Writer Scott Gimple and director Michael Satrazemis distracted us with the tension of whether or not Carol (Melissa McBride) would confess to Tyreese (Chad Coleman) that she killed and burned his ex-girlfriend’s body. They have an emotional talk in the woods, then come back to Lizzie, Mika, and Judith in the yard of the house where they’re staying.

But Mika isn’t moving. And Lizzie’s hands are covered in blood. Lizzie has just offed her sister to show that she’ll “come back” and still be Mika. She would have done the same to Judith, except that Carol and Tyreese interrupted her. The only solution to this problem is instantly clear—this kid has got to die.

Carol does it Of Mice and Men style, leading Lizzie out to pick flowers and talk. Lizzie breaks down crying because she thinks Carol is “mad” at her and Carol comforts her. She tells Lizzie to “look at the flowers” and, as Lizzie’s back is turned, Carol takes out her revolver…and shoots her.

It’s a harrowing scene played exceptionally well by Melissa McBride, the show’s strongest actress, with the fatigue of losing so many children (Lizzie counts as the third “daughter” Carol has lost) etched all over her face. But it’s also sad for a different reason: In losing Lizzie, we’ve lost one of the show’s most interesting perspectives.

Lizzie was unlike any other character, in that she actually sympathized with walkers and thought of them as her friends. She even had a “favorite walker” back at the prison, which she fed mice to, like it was a pet (another John Steinbeck reference!). This episode’s cold opening, which showed Lizzie frolicking with a zombie, was effective in the way that all of Lizzie’s stories have been so far: It was demented and strange—and endlessly fascinating. How freakishly well some kids have adapted to the world after zombies is an angle now left to Carl. Selfish, whiny, boring Carl.

Why Lizzie chose this episode of all episodes to snap is unclear. She spent all season yammering about why walkers aren’t dangerous, just “different”—so why kill her sister now? It’s also confusing that she doesn’t just kill herself to prove the point—if she’s so convinced that walkers are still human (and we see her consider becoming one while she’s out feeding one by the train tracks), wouldn’t it have made sense to do it to herself? I guess The Walking Dead draws the line at child suicide.

Carol and Tyreese are now back on their way to “sanctuary” Terminus, which is obviously too good to be true. We’ll wait to see what horrors await there, but it’s going to be hard to top the one we witnessed last night.