Brent Bruns II loves downtown St. Petersburg.

"We're in paradise down here,” said the 41-year-old who runs a Facebook page dedicated to the area. "There's no reason to go up to this middle-of-the-woods castle that I hate.”

He is referring to the doomsday castle his dad is building in the Carolina mountains. Bruns II changed his mind, though, when his father, Brent Bruns Sr., made the family an offer.

"I put a challenge out to my children. I said, 'Come up and spend two or three months with me. Help me build this castle and let's see how well you do,'” said Bruns Sr. in a promotional video for the National Geographic Channel’s reality show, "Doomsday Castle."

The younger Bruns decided it was an opportunity to develop a relationship with his father and siblings and decided to take the chance.

His life, as he describes it, was far from perfect at the time.

"You'll see the first few episodes I look pretty bad,” said Bruns II.

He was battling a prescription pill addiction and he credits the experience at the Castle for his personal rehabilitation.

“It really took separating me from this location, from the party friends that I had, and going up to that mountain to that castle to kinda snap me out of a three year problem,” he said.

His sister, Lindsey, who now lives with him, was along for the ride as well as three of their other siblings.

"And there you have us the Brady Bunch meets Adam's Family!” said Lindsey, as she described what the experience was like. "I hope that people are really going to enjoy the show and just realize this wasn't about the money, this isn't about the fame. And this isn't something that we decided to do because the opportunity arose. My dad's been doing this for the past 13 years, building this castle."  

Bruns Sr. decided to buy a mountaintop for a doomsday castle in 1999 just before Y2K.

Bruns II wrote the National Geographic Channel about the castle and they became one of the most watched episodes of "Doomsday Preppers." "Doomsday Castle" is NGC’s first spin-off series.

"Doomsday Castle" airs Tuesdays at 10 p.m.