The Walking Dead Kills Off Main Cast Member After Shocking Betrayal

We're going to immediately jump into spoiler territory here, so if you haven't watched Sunday's new episode of "The Walking Dead" yet, you've been warned!

Viewers said goodbye to a series regular, after a major a-ha moment led to a deadly showdown between two characters in the hour's final moments. Yes, Siddiq (Avi Nash) is dead, so it only seems fitting to start this recap by breaking down how he met his end.

To see what star Avi Nash had to say about his shocking exit, check out our new interview with him right here:

As has been the case since he emerged as the sole survivor of the Whisperer attack on fair day, Siddiq continued to have nightmares and battle his ongoing PTSD. This time, however, some of his repressed memories from the slaughter began to come back to him.

As this was happening, Carol returned to Alexandria with a Whisperer prisoner. He quickly fell ill once behind bars and died, after consuming hemlock. Dante -- who administered what he said he thought were painkillers to the man -- pointed the finger at Siddiq, claiming he packed the medical bag. We'd later learn this was a lie.

Believing he screwed up big time, Siddiq's panic attacks continued to get worse. Eventually, he jumped into Alexandria's water supply to drown out all the noise, only to have Rosita save him from literally drowning. "Do you know why it bothers me so much? Enid. I just think about how much I miss her, but I get to remember how I failed her," he then told her, revealing his survivor's guilt.

"People that I love died right in front of me and now I get to watch it over and over and over and I did nothing. I didn't move. I didn't help. I just watched," he told her, something else we would later learn was not exactly the case. While speaking with Rosita by the pond, he pieced together that the water was the common denominator for all the sick people in town. Upon investigation, he confirmed someone inside the community jacked up the handles for the purification system, so they'd been drinking contaminated H2O.

Still feeling responsible for so much that was going wrong, Siddiq retreated into his room, where Dante came to console him. He tried to talk Siddiq off a ledge, saying he wasn't to blame and it "takes a village" to keep everything running smoothly. But then something clicked, literally, for Siddiq as Dante began making clicking noises in his mouth.

That noise triggered a flashback to being inside the barn, as the Whisperers killed his friends around him. One of the skin-wearers was making that same clicking sound, as the mystery man held him down, preventing him from fighting back. With that, Siddiq's whole demeanor changed and he charged at Dante, who was more than ready to fight back. As he choked Siddiq to death, however, Dante made it clear this is not the outcome he hoped for. "I didn't want this. Not you, not like this," he said, after having made some kind of real bond with someone in the community he was sent to spy on.

The question now: just how long will Dante be able to keep his cover ... and how will Siddiq's death be explained?

Dearly departed Siddiq wasn't the only one dealing directly with Whisperers this week, however.

Carol's plan to get intel out of her prisoner was derailed by Dante poisoning him, but she did get a key piece of information from him before his death: The Whisperers all believe Alpha killed Lydia.

While Daryl pleaded with Carol to not bring Lydia into her own vendetta against Alpha, Carol just couldn't help herself. Taking her out of Alexandria on false pretenses, the two stumbled upon Gamma holding up Aaron at knifepoint. Though Gamma and Aaron had bonded in the woods earlier about children and siblings, Alpha made her believe Aaron was just lying to "seduce" her to their side.

After saving Aaron from Gamma's attack, Lydia then popped out -- and the sight of her shook Gamma to her core. You could sense the betrayal Alpha's little helper felt in that moment, as she ran off into the woods. Clearly, this will have huge ramifications back at the Whisperer's camp, if and when they all learn their leader lied to them about something this big.

Though Carol seemed pleased with herself, Lydia was pissed when she realized she had been used. "You're just like her," she shouted, comparing Carol to her own, evil mom. "You said you wanted me to choose a side, I choose mine." She then socked Carol in the face, before running off.

As we head into the mid-season finale, where will Lydia end up and how will Daryl react to what Carol has done?