The Walking Dead raises the stakes in season ten with a devastating, killer reveal. "Open Your Eyes" lifts the veil on a Whisperer infiltrator, who murders a primary character when discovered. Carol (Melissa McBride) and Daryl (Norman Reedus) struggle with a difficult prisoner. Siddiq (Avi Nash) continues to suffer PTSD while investigating the mysterious illness. Gamma (Thora Birch) begins to interact with Aaron (Ross Marquand). Carol has a new use for Lydia (Cassady McClincy).

"Open Your Eyes" is whispered as Siddiq has another gruesome flashback. He awakens in a chair, then tends to a critically ill Cheryl (Rebecca Koon). He visits Rosita (Christian Serratos) next, before stopping to refill a jug of water. He pours water at the clinic, now overrun with sick Alexandrians. He sees Alpha (Samantha Morton) for a flicker at the window. In his study that night, he struggles to understand the sickness. Arms tear out of the chair and grab him screaming.

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Daryl kicks Lydia out of the cell, so they can hold the Whisperer prisoner (James Parks). Lydia warns them he will say nothing. Father Gabriel is furious at Carol for what she's done. He demands to be present during the interrogation. Carol asks Daryl if he wants to sit this one out. Daryl relaxes with dog, then sees the joined acorn Carol found.

On top of the mill, Carol gives Lydia back her sword. She plies her for more info about the prisoner. Lydia replies that only her mother's most faithful followers watch the "horde." She says her mother "twists people" to do her bidding.

Siddiq and Dante (Juan Javier Cardenas) treat the prisoner in his cell. Siddiq is unnerved by the Whisperer. Father Gabriel and Dante ask him to go outside. He sees the spiked fence and flashes back again to Alpha's beheadings.

Aaron and Gamma stand across from each other on the bridge. He offers her bread. She's surprised they have it every day. He shows her a painting from Gracie, his daughter. He asks if Gamma has children or siblings. She responds, "I am an only child."

Carol sits in front of the prisoner. She gives him a piece of bread covered with multiple jams. The prisoner lights up at the sight of the food. He relishes the sweet bread in his mouth, and then spits it back into Carol's face. Siddiq checks on Rosita. He lies with her in bed as she regrets missing her radio appointment with Eugene.

In the cell, Carol sticks her thumb in the prisoner's wound. She puts on her wedding ring and pummels his face. Daryl stops her. The prisoner mocks them. Daryl threatens to cut off his body parts. The prisoner is not moved, "I would never betray Alpha. She sacrificed her own daughter for us." Carol realizes they think Alpha killed Lydia.

Carol goes to get Lydia, despite Daryl's objections. Siddiq cares for Cheryl, who asks him to close his eyes and rest. At the bridge, Aaron gives Gamma the painting. Gamma accidentally slips that she had a sibling. Aaron brings up how his younger brother was killed. He asks her to drop the probing for information. They can just talk about nothing. Gamma walks away hurriedly.

In the cell, the prisoner is violently ill. Father Gabriel brings Siddiq and Dante to treat him. The prisoner convulses, coughs up blood, and dies; right before Lydia is brought in. Siddiq realizes that Dante gave the prisoner hemlock. Dante is shocked by the mistake. He says Siddiq packed the medical bag.

In the woods, Gamma kills a walker after a brief struggle. Alpha sees this and chastises her for "one less guardian." She updates Alpha on Aaron. Alpha wonders if she asked about her sister's child. Alpha demands Gamma remove her mask. She lashes her arm with a switch, "We are always being tested. We must be strong." She ends the punishment with a kind, "I believe in you." Do not be tempted by Aaron's lies.

In the cell, Daryl and Father Gabriel clean up the prisoner's dead body. Carol and Lydia are on horseback riding. Siddiq checks on Cheryl, but she has died. Dante is burying her body. Siddiq returns home but becomes faint. He sees Enid being killed in a flashback. He runs towards the water and jumps in. He hears "open your eyes" as Enid screams. Rosita dives into the water and pulls him out.

On the dock, Rosita forces Siddiq to talk. He admits to being overcome by guilt for watching their friends die. He's "still there, all the time." He doesn't understand why people are dying now. He also admits to disliking Dante because he replaced Enid. Rosita gives him tough love. He has to get over this. They need him.

Siddiq goes back to the water pumps. He notices the lever that switches the drinking water with potable water has been tampered with. He goes berserk and starts smashing a table. That night on the bridge, Gamma refuses anything else from Aaron. She puts a knife to his throat, but Carol arrives with Lydia. Gamma is shocked to see Lydia alive. She lets Aaron go and runs away crying. Carol wanted Gamma to see Alpha lied. Lydia is furious. She chooses a side, hers. Lydia hits Carol when she approaches, then runs away into the dark forest. Gamma sits alone crying hysterically.

Siddiq is in his room, looking through the glass. Dante comes in to talk. He wants to affirm their friendship, pull his weight more. Siddiq blames himself for the deaths. As Dante speaks, Siddiq closes his eyes and flashes back again. He remembers a Whisperer holding his head as Enid was killed, telling him to open his eyes. Dante says the same thing. He looks back and realizes that Dante was the Whisperer. They fight viciously in the room. Dante puts Siddiq in a chokehold. He whispers "close your eyes" as Siddiq is murdered.

Dante has been switching the drinking water and poisoning the Alexandrians. This is why Alpha had Gamma gutting the walkers in the streams. He is definitely not following the character arc from the comics. Siddiq's death was brutal and heartbreaking. I had a feeling he was doomed, but no one saw Dante's betrayal coming. He also cleverly silenced the prisoner. Alpha's been a step ahead, but her grip over Gamma is shattered. Lydia loose in the woods is sure to be a problem. The Walking Dead has built up to an epic midseason finale, next week on AMC.

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