The Walking Dead turned in a thrilling, action-packed episode with Season 10, Episode 10. "Stalker" had big developments for Alpha (Samantha Morton), Gamma (Thora Birch), Lydia (Cassady McClincy), Father Gabriel (Seth Gilliam), and Rosita (Christian Serratos). It was a fast-paced episode with the best jolt moment of the season to date. (I want to call it a "jump scare," but that's not exactly right, because it wasn't a scare.)

It's hard to say which of the episode's two plots were more important, especially since they were pretty interconnected. So we'll start with the Alexandria side of the story.

Gamma, the Whisperer turncoat, showed up at Alexandria's gate with a warning that Aaron (Ross Marquand) and the rest of the cave crew were in trouble, as Alpha had lured them into the cave with her walker horde inside. Gabriel and Rosita didn't believe her, as she had previously said the horde was in a field and they were skeptical Alpha would have been able to move that many walkers into a cave that quickly. So they locked her in Alexandria's jail cell — that place is never empty for long! — and said they would kill her if she couldn't convince them she was telling the truth.

"You'd be the third, by the way," Gabriel said. After cold-bloodedly murdering the Whisperer spy Dante (Juan Javier Cardenas) in retaliation for killing Siddiq (Avi Nash), Gabe has a bit of a taste for Whisperer blood now. Dante's blood was still on the floor of the cell, as Siddiq's death was only two days ago in The Walking Dead's timeline. Gamma was able to convince Gabriel she was telling the truth by being honest about how her sister, the mother of the baby the Whisperers abandoned at Hilltop last season, died: Gamma killed her. "I killed her for Alpha," Gamma said through tears of pain and regret. "She didn't even have to ask, I just did it."

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Gamma showed the Alexandrians where the cave was on a map, and after she was taken back to the cell, Gabriel told the skeptical other council members that he knew she was telling the truth because she was afraid, and the Whisperers are cowards. They'll cave under pressure and give up intelligence, so if they encounter any, they should "cut off their fingers, pull out their teeth" to make them talk. Rosita was disturbed by her boyfriend's savagery, and worried that his anger would get him into an ill-advised fight, and she can't afford to lose him, too.

Back in the cell, Gamma connected with Judith (Cailey Fleming), who talked to her through the basement window. Judith asked her her name. "Nobody has asked me since I got here," Gamma said. "It's Mary." She doesn't remember much of her life before she met Alpha, just that she and her sister were making bad decisions at the start of the apocalypse and they needed someone to lead them, and that turned out to be Alpha. "You met the wrong person first," Judith said. "If you'd met my mom or my dad you wouldn't be in that cell. You don't look like a monster to me."

A report came over the radio that a herd was on its way toward Alexandria, so Gabriel and Rosita and the rest prepared to head out to fight it. Rosita seemed shook, so Gabriel told her to stay behind and watch the gate while he led the team outside the walls. She told him she'd been having nightmares about Whisperers killing Coco, and she wouldn't trust herself out there. He kissed her goodbye and gave her his hat. That gesture, combined with a reference to a watch tower a few miles away, a location very significant to Father Gabriel in the comics, made me worry that Gabe wasn't going to make it back.

But the fight wasn't outside Alexandria's walls, it was inside. Beta (Ryan Hurst), sent by Alpha to get Gamma/Mary, snuck inside Alexandria using a secret tunnel that Dante must have helped dig. Under the cover of darkness, he stalked through Alexandria, slipping into houses and killing everyone inside, which was easy, as most of the fighters were gone. He found Mary and told her to come with him, because Alpha wanted to see her. He was interrupted by Laura (Lindsley Register), who put a blade to his throat. While he was fighting her, eventually bashing her head against the wall, Mary escaped, and Judith called her inside her house.

Beta followed her inside, and for an agonizingly tense minute and 20 seconds of total silence, he moved through the house looking for her. The silence was broken by a sudden, shocking gunshot, as Judith shot him through a door. She and RJ escaped as Beta played dead, but he knocked Mary down and pulled the bullet out of his bulletproof vest as he rose over her unconscious body. Rosita appeared and tangled with him. She put up a fight, but the hulking brute overpowered her, and as he was about to kill her, Mary got his attention by putting a knife to her throat. "Alpha wants me alive," she reminded him.

They left Alexandria and were ambushed by Gabriel and his crew on the road. Beta fled into the woods, but Gabriel believed Mary when she told him she hadn't betrayed Alexandria. The next morning, she, Rosita, Judith, and RJ set off for Hilltop. Rosita was going to see the doctor, and left Coco with Gabriel. She introduced herself to Mary as a friend, because Mary had proven herself. Mary was going to see her nephew.

Seth Gilliam and Kenric Green, <em>The Walking Dead</em>Seth Gilliam and Kenric Green, The Walking Dead

The other half of the episode featured Alpha and Daryl (Norman Reedus), which was equally tense. Daryl tracked a Whisperer to the mouth of the cave, where he saw Alpha and some other Whisperers were drawing walkers out. He followed them for a bit and attacked them as they led the herd up the middle of a shallow creek. He killed all of the Whisperers except Alpha, though he and Alpha beat the absolute snot out of each other. He stabbed her in the shoulder with a branch, and she stuck him in the leg with a knife. They were both severely injured, and they took shelter from the herd in an abandoned garage.

Daryl was hiding from Alpha, who was too hurt and tired to move too much and find him. She banged her sawed-off shotgun against a metal doorframe to draw walker attention. Three really disgusting walkers came — one had mushrooms growing all over his body — and Daryl dispatched Ol' Shroomy with the knife he pulled out of his leg.

They were both exhausted and losing a lot of blood. Alpha started to see visions of the people who hard hurt her and made her strong. "Pain made me, pain made you," she said to Daryl. "Pain made my Lydia."

"You lost her," Daryl grunted. "You drove her away because you didn't love her."

This infuriated Alpha, and she staggered away from where she was sitting to try to get him, but she fell down. As she lay there, Lydia appeared.

"Are you really here?" Alpha asked.

"Yes, Mama," Lydia said. The prodigal daughter had returned, after running away in Episode 7 to avoid having to pick a side between her mother and her new friends.

"Don't call me that, you know better," Alpha said, though with more affection than she typically shows her daughter, almost like she had missed her so much she even missed the things about her daughter that made her angry. "You came home. I am you and you are me." She sang "Lydia the Tattooed Lady" to her daughter like she did when Lydia was little, and put her knife in Lydia's hand. She wanted Lydia to kill her.

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"They're waiting for you to lead," she said. Lydia couldn't go through with it, but she did tell her mother that she wasn't in that abandoned garage for her or the Whisperers. She was there for Daryl. "They're human," Lydia said. "Not perfect, just human. That's all I ever wanted. That's what you never gave me."

Alpha passed out, and when she came to the next morning, she was a little stronger, but Lydia and Daryl were gone. Lydia had left her knife, but carved "YOUR WAY IS NOT THE ONLY WAY" into the table.

Daryl came to in the woods and asked Lydia if she had killed her mother. "If it was your father, could you have?" she answered. Daryl and Lydia had similarly abusive upbringings, and they understand each other's pain. They know it's not pain itself that makes them strong, it's sharing the burden with other people.

Alpha was found in the building by some Whisperers who tended to her. "I am no longer weak," she said, to no one in particular. "I'm stronger than ever. Our horde will butcher and consume them. Screams will be song to me." Then she did that creepy "We are the end of the world" prayer. She has turned her back on her daughter once and for all, and Alexandria and Hilltop will pay the price. The one thing keeping Alpha a little bit restrained is gone. Scary.

The Walking Dead airs Sundays at 9/8c on AMC.

Samantha Morton, <em>The Walking Dead</em>Samantha Morton, The Walking Dead