Robert Kirkman opens up on Invincible season 4's show-original Hell storyline – and why it will shape future seasons

Invincible is going to Hell.

As teased during the Invincible season 3 ending, Mark Grayson is suddenly in the sights of a pair of devilish figures, Clancy Brown's Damien Darkblood (last seen being banished in the first season) and Satan, voiced by Bruce Campbell.

In this case, even long-term fans won't know what comes next. The Hell storyline in Invincible season 4 is a show-original arc taken from an idea that creator Robert Kirkman never got round to during its initial comic run.

Speaking to SFX magazine, Kirkman teased, "What was going on in Hell, and what Hell is in the Invincible universe, I think will come as a surprise to some people."

To that end, Kirkman – also known for bringing The Walking Dead to life – revealed that the Hell episode (and, much like other big concept episodes in the past, it does sound like only a one-episode concern) will leave plenty of narrative breadcrumbs for the Prime Video superhero series to pick up down the line.

"I can't help but leave dangling threads that hopefully will come back in the future," Kirkman said. "There's probably three or four longrunning subplots that are set up or hinted at in that episode. To what level we address them as the future goes on remains to be seen."

If Hell wasn't bad enough, Invincible season 4 also introduces series Big Bad Thragg, voiced by Lee Pace as the full might of the Viltrumite Empire comes crashing down on Mark and his father, Omni-Man.

Invincible season 4 premieres on Prime Video on March 18. For more, check out the best shows on Prime Video you should watch right now.