Maggie stood defiant as the Saviors prepared to assault Hilltop, but she had no idea just how devastating the attack would get.

Simon came armed with weapons that have been tainted with walker guts, allowing the undead to rise behind the community's walls.

“This is really the Saviors' first big strike. It's a pretty evil plan,” says Executive Producer Greg Nicotero in a new behind-the-scenes video.

Go Inside Episode 13 “Do Not Send Us Astray” With the Cast and Creators

“The stakes are raised infinitely higher because of this biological warfare that Negan is using against our people,” he adds.

The plan unleashes havoc on the Hilltop and Maggie must watch as Hilltop’s graveyard gets bigger.

“As a leader she feels responsible for each and every one of those deaths,” says Executive Producer Tom Luse.

But no matter the cost, Maggie is still driven by one goal: eliminate Negan.

“Of everyone who wants to take Negan out, Rick and Maggie are the two who want it the most,” says Co-Executive Producer Denise Huth. “It doesn't matter who else dies.”

Click here to see the cast and creators break down the Saviors' brutal attack on the Hilltop.

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