'The 100' season 4 news, premiere spoilers: Showrunner hints 'dark' and 'relentless' plot; Clarke needs to find way to save everyone

After pitting its characters against each other, "The 100" returns to its survivalist roots when the post-apocalyptic drama returns for its fourth season this week.

After season 3 saw how a narrow-minded leader got the Sky People in trouble, season 4 picks up with the heroes facing their biggest enemy yet. The nuclear power plants begin to melt down, releasing waves of radiation that could make Earth entirely uninhabitable. This challenge is unlike anything Clarke (Eliza Taylor) and the rest of the group have faced before as it forces them to decide between saving themselves or saving the whole world.

With only six months before doomsday, the plot for season 4 likely put viewers on the edge of their seats as they witness how Clarke and the rest of the characters deal with the possibility of their own extinction. Showrunner Jason Rothenberg recently caught up with Hypable, and he revealed that despite the major problem faced by the survivors, this season will not be totally nihilistic.

"There's a more hopeful feeling to this season overall, despite this horrible thing they're facing. You know, they say there are no atheists in foxholes," he explained. "You find out what you believe and who you are when you stare down the barrel of a gun, and they've got one coming at them pretty quickly. So this season is dark and relentless, certainly, but it's also surprisingly hopeful," the showrunner added.

As fans know, the characters follow a strict status quo where everyone is loyal to their own clan. Given the new situation, Rothenberg hinted that it will certainly change where people's loyalties are and influence how alliances are built or broken. The new episodes will explore how Clarke tries to figure out a way to save as many people as she could.

"You save your family first, of course. You save your country first, of course. We all are patriotic," he continued, adding, "But at the end of the day, when the thing that's coming for you is going to kill everybody, can you figure out a way to link arms together and face it together? That's what this season's about."

The fourth season of "The 100" premieres on Wednesday, Feb. 1, at 9 p.m. ET on The CW.