The mysteries in and out of Chester's Mill have been bugging fans of "Under the Dome" ever since the second season wrapped up, but not for long. Season 3 of the sci-fi thriller, based on Stephen King's book of the same name, will be back in summer to unearth some shocking revelations. 

"We will tell you why the dome came down and what it's about," executive producer Neal Baer told TV Line. "By the end of the season, you'll know exactly why this happened the way that it happened." 

To quench fans' thirst for answers, CBS has released a preview of "Under the Dome" season 3, where Big Jim and Julia are shown planning to help the citizens of Chester's Mill from the dome, which the former cryptically revealed is there "to destroy" them.  

Co-showrunner Tim Schlattmann also hinted at what's in store for fans in the new season, promising some answers to some of the show's biggest questions and mysteries. 

"Why was there 25 years to pass before the dome came down? What was in play 25 years ago that set all this in motion? That's one of the biggies we're going to address," Schlattmann revealed. "You'll see how these puzzle pieces form a puzzle that may be different from what you thought it would be." 

The new season will also be life-changing for Dale, who is rumored to be the father to someone's child, someone fans never expected. This will make things more challenging and interesting for the character in the face of an apocalyptic chaos. 

Meanwhile, viewers who happen to be "ER" fans can look forward to the mini reunion of Eriq La Salle, who plays Aktaion Energy CEO Hektor Martin, and Paul McCrane, who will guest-star in at least one season 3 episode as an incredibly brilliant scientist named Danville. 

Here is the synopsis for the new season:

It's been two weeks since the dome descended upon the sleepy town of Chester's Mill, whose inhabitants are still struggling to survive with resources running low as their search for answers to what the barrier is and where it came from continues. The post-apocalyptic conditions intensify while the residents must decide who to rally behind as new faces emerge and Big Jim continues to battle for the town's trust and allegiance. With survival hanging in the balance, can the residents of Chester's Mill work together to protect their uncertain future?" 

"Under the Dome" season 3 will premiere on June 25.