“Under the Dome” sure does how to get our hearts racing before bed. During tonight’s episode, “In The Dark,” a lot of drama went down – including a seriously shocking death. And lucky for you we’ve recapped the entire episode 6, including the breakdown of a Chester’s Mill resident's surprising demise.

Episode 6 begins with Junior diving head first into the mysterious tunnel he found hidden inside Melanie’s locker. Apparently the passage leads to a basement that’s covered with footprints – Lyle’s footprints, or at least that’s what Junior thinks. Rebecca begs for Junior and Sam to come back up from the hole but Junior is on a mission to seek vengeance for the death of Angie.

After they descend Rebecca immediately calls Barbie for help, which totally irks Big Jim who’s listening in. We guess “Jimcca” is officially over. Barbie races to the scene and ends up startling Junior and Sam in the tunnel. But despite Barbie’s surprising debut, the three continue their journey throughout the mysterious tunnel. Well, until Junior sets off a trap in attempt to retrieve his mother’s journal.

As Junior runs to grab his mom’s diary, rubble begins to fall. Barbie rushes to push Junior out of the way of falling rocks but he and Sam both get caught underneath the fallen pillars.

Thankfully all three survive the cave in but now Junior is trapped on one side while Sam and Barbie are on the unknown other. Sam places the blame of the trap -- and the death of Angie -- on Lyle but Barbie doesn’t buy it. The two then divulge on the topic of Lyle a little further. Sam says he knew Lyle when they were friends way back when but eventually they just grew a part.

But that’s only the beginning of Sam and Barbie’s tumultuous relationship. Eventually Barbie calls Sam out for dating Melanie 25 years ago. He asks why Sam never mentioned his ex-girlfriend coming back from the dead. Sam rebuttals saying that the residents of Chester’s Mill would have thought he was crazy if he did.

At that moment, Barbie nearly falls off a cliff. Sam has the choice of dropping him or pulling him back up – thankfully Sam chooses life and drags Barbie up to safety. Why would Sam save Barbie when Barbie knows too much for his own good?

Meanwhile, outside, there’s a huge dust bowl a-brewin’ and rumor has it it’s going to suffocate the town’s people of Chester’s Mil if they don’t do something. Eventually the town‘s people agree with Big Jim’s plan to put up a moisturizing-windmill -- per Rebecca’s advice.

Back in the dark, Sam claims that the only reason Barbie is suspicious of him is because he’s hanging out with Julia. Barbie says he’s not far off. Next thing we know the trapped duo are talking about what really happened to Melanie the night she allegedly she died.

“The egg started screaming. Pauline grabbed [Melanie’s] head and said it’s killing me. I tried to get the egg but Melanie wouldn’t let it go. Lyle went after her. I let him,” Sam explained. “He pushed her. Her head hit the meteorite. Pauline begged me to help Lyle. I did. I left the love of my life in hole like garbage and now she’s back.”

Under the Dome season 2 spoilers Find out what happened in episode 6 of "Under the Dome." Photo: Screen Grab/CBS©2014

“So why is Melanie back now? To haunt me? To bring me pain? Every day is a new nightmare,” Sam says, referring to the dome as some sort of execution.

The two reveal they’ve both played a hand in death, bonding over their troubling experiences. That is until Barbie sees scratches on Sam’s chest.

“Those aren’t from rocks,” Barbie says, getting a closer look at Sam’s wound. Sam pushes him off. “Those are defensive wounds. Angie was a fighter. You killed her Sam -- not Lyle.”

Sam says Lyle is a maniac.

“You killed a 19-year-old girl that your nephew loved,” Barbie says.

“I had to,” Sam says, finally owning up to what he did. He also reveals that he’ll find a way to eventually kill the final three -- including Junior. Sam then makes the shocking revelation that once the dome comes down he’ll take his own life.

But Barbie won’t let that happen. He wants to bring Sam back to Chester’s Mill to receive the justice he deserves -- particularly at the hand of Junior.

“When you watch Julia die you’ll put the knife to those kids yourself,” he says before jumping off the ledge.

That’s when Julia and Rebecca blow through the rubble and find Barbie – alone.

“Where’s Sam?” Julia asks.

“He’s gone,” Barbie responds, not revealing Sam had just committed suicide.

What did you think of episode 6 of “Under the Dome”? Do you think Sam is really dead? Do you buy his story that Lyle is the one who killed Melanie? Sound off in the comments section with your theories.