If you haven’t heard yet, Prime Video’s new series Fallout, an adaptation of the super-popular video game from showrunners Geneva Robertson-Dworet and Graham Wagner, is a critical smash. It’s currently sitting at 94% fresh on Rotten Tomatoes, with critics hailing its vivid and captivating universe, its fearless weirdness, and its singular approach to transforming a world well-known to millions of gamers into a universe accessible to newcomers. In short, Fallout is a blast.

In a new video, Walter Goggins takes us behind the scenes of the creation of one of the two characters he plays, the radiated, post-apocalyptic gunslinger called The Ghoul. Fallout is set 200 years into the future after a nuclear war. “The Ghoul is a bridge between the world before the nuclear fallout and this world that we find ourselves in,” Goggins says.

The post-nuke world The Ghoul lives in is not pretty. In fact, it’s “kill or be killed,” as Goggins explains, a vast, dangerous radioactive wasteland where the insects and animals have been transformed into monstrous versions of themselves and the humans, well, they’re even crazier. Goggins also plays Cooper Howard, a gentle husband, father, and actor in 1955 who starts the series entertaining at a children’s birthday party, one that ends on a sour note—a nuclear bomb explodes in Los Angeles. There goes the end of the world, the end of Cooper Howard, and the start of Fallout. Yet Cooper doesn’t die, however—he transforms—and 200 years later, he’s still lurking about, a changed man, noseless, his skin a livid red, and his gentleness exchanged for a ruthlessness and a will to survive as The Ghoul.

To turn Goggins into The Ghoul required the mastery of special effects makeup artist Jake Garber, who Goggins calls “one of the best special effects makeup artists in the world.” The incredible artistry on display here allows Goggins’ Ghoul to really look like a man who was transformed by radiation into a nearly timeless, monstrous version of his former self, yet the true genius of Garber’s work is that it doesn’t obscure the Ghoul’s humanity or pile so much makeup onto Goggins that we can’t see the nuances of his performance.

“Walton completely embodies the character, and it can be pretty terrifying working opposite him,” says Fallout star Ella Purnell.

Check out Goggin’s transformation into The Ghoul below. Fallout is streaming on Prime Video now: