"We'd shot the pilot but, really, it was still a shot-in-the-dark situation," explains Slater. "And then the Sony hack happened, which really brought it to everybody's attention and made [hacking] much more of a mainstream topic.
"As we continued to shoot episodes it continued to mirror things that were actually happening in the world, and next thing you know, US newspapers are calling Sam [Sam Esmail, Mr Robot's writer and director] and saying, 'Hey, what can you tell us about this?'"
Breakthrough star Rami Malek, who plays Alderson, never expected the series to catch on like it has.
"When I read the script, I was like, is someone really going to make this? The things we were saying were so forward and aggressive," he says.
"I figured it would have a cult following in 10 years, but it was a life-changing moment to discover that it was having that kind of impact, not just as entertainment, but as a thought-provoking experience."
For Malek, the role has been particularly life altering, bringing a slew of awards nominations, and catapulting him into the public eye.
"People look at me on the street now and I don't know if they differentiate between me and Elliot, but there's sometimes this look of 'there's our little hero'," says Malek.
"That's a cool experience. I get to play a guy who, every day, challenges me emotionally. He's a gift, not just for an actor, but because the things I get to say from a cultural standpoint are so poignant and powerful. It's not lost on me how cool this guy is."
It's overwhelming, he says, to be playing Elliot during an American election year and moment in the culture rampant with the false idols the character rails against (even the supposedly squeaky-clean Steve Jobs comes in for vitriol).
Esmail was, from a young age, fascinated by hacking and heavily influenced by the Arab Spring, which was partly masterminded online by young, angry, digitally savvy activists (both Esmail and Malek are Egyptian-American).
The show has a hacker advisory team that includes Michael Bazzell, a former FBI cybercrime investigator, which lends a technical verisimilitude to the narrative.
The onscreen code is real, but the world of the series feels credible in other ways too -- Evil Corp's ubiquitous logo was lifted from Enron, but could substitute for Apple, Microsoft, GM or any of those perfect monsters that now colonise our visual landscape.
At the same time, it's often hard to tell what's real because much of the action is taking place in Elliot's head, and he's far from a reliable witness. Slater's Mr Robot is eventually revealed -- via Elliot's flashbacks -- to be a larger-than-life, 2.0 version of his deceased father, Edward (sort of). By the end of the season, Evil Corp has taken a big hit and Mr Robot's hacktivist-led revolution has begun, with people taking to the streets in the Guy Fawkes masks adopted by anti-establishment movements in real life, including Anonymous and Occupy.
The theatrical and mysterious denouement, filmed amid Times Square's glowing walls of advertising, sees Slater in balls-out Hard Harry declamatory mode against the "kingdom of bullshit" that is the modern world.
"Sam [Esmail] definitely referred to those anarchist-type guys fighting against an unjust system," says Slater. "I love those characters, and it's been interesting to look back at those films, the technology they had, and what the stakes were. I mean, [Hard Harry] had a ham radio and was trying to deal with the school principal.
"Now the stakes are higher and the technology is incredible, it's escalated beyond belief."
Naturally, the finale left us with more questions than it answered - and the lips of the stars are, predictably, sealed.
What: Mr Robot season 2
Where: Lightbox
Where: From today
