The third season of TNT’s Snowpiercer debuts Monday night at 9 p.m. ET. The action-packed drama concerns a massive train carrying the last remnants of humanity on a non-stop journey around the globe, after the entire planet becomes a frozen wasteland. It’s a high-concept plot, but star Daveed Diggs believes that everyone can see themselves in Snowpiercer‘s diverse cast.

Diggs plays Andre Layton, a former detective who leads a rebellion against the train’s oppressive class system and its maniacal designer, played by Sean Bean. “There are a lot of points of entry for people,” Diggs tells ABC Audio.

“Every actor on there is giving these characters really full, lived experiences…and so I think there are a lot of ways to find yourself on Snowpiercer,” he explains. “It’s a pretty representative group of people…[and] if you have an ‘in’ to a story, then all of a sudden you can participate in it.”

And that representation has literally changed lives. Mickey Sumner plays security guard-turned-rebel Bess Till, who’s gay. Sumner says, “I had actually a woman reach out who was a cop, and she told me that because of Bess Till, she was able to come out to her colleagues at work and her family.”

Sumner’s amazed by the show’s fan engagement: Viewers create Snowpiercer-inspired artwork and dissect every plot detail online.

“People become really attached to these characters and really own them,” she says. “And I love that.”

But Snowpiercer‘s also a cautionary tale.

“This is an allegory of the present,” says Sumner ruefully. “There’s a lot of warnings about what not to do. And there’s also, sadly, lot, of similarities about how we treat people and how leadership fails people. So it’s been really interesting, at this time, to be part of this show.”