When Andy Mackenzine walked into his audition for season 2 of "True Detective" he didn't know what to expect.

"I read for a couple of roles at once...The process took quite some time.... Then I got the call that I got a role," Mackenzie told CBS News.

But he still wasn't sure exactly which role.

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In the end, the part was for Vince Vaughn's lead henchman, Ivar. Vaughn plays Frank Semyon, a career criminal in danger of losing his empire following the murder of his business partner, Ben Caspere. Throughout the murder investigation and the drama that unfolds afterwards, Ivar is right by Frank's side. Mackenzie has appeared in the first three episodes of the HBO series thus far.

Mackenzie says from the very beginning, everything about the show has been kept very much under wraps.

"[It was] total secrecy -- I had to sign the non-disclosure agreement. Everything was changed -- aliases, title changes, everything.... Every time you need to sign those kinds of agreements you know there's something good behind it," said Mackenzie. "I had finally gotten the script, but I didn't know what I was playing exactly. It's just the way it is -- the nature of this particular beast."

Mackenzie soon learned that his Ivar character would be from "somewhere in the Eastern European region."

"When I read the character description he's speaking in different kind of tongue. So, he's speaking broken English. Which is fun," said Mackenzie, who has guest starred through the years on shows including "CSI: Miami," "NCIS: LA," "True Blood," and "The Practice."

"When I got to set and I talked to [show creator] Nic [Pizzolatto] about it, he had given me the go-ahead to do [what I wanted with the character]. 'If you think you can do Russian, do it!' he said. And I actually learned Russian. When I was in high school, I went to Leningrad when it was still Leningrad and spent some time there. And I nearly got fluent in Russian. So, it was nice to hear from Nic -- 'I believe in you.'"

Once they started filming, details of each episode were kept very hush-hush.

"The secrecy of this, it started from episode 1. I read the first script for the first episode and after that, nothing. Only pages the day before I got there...Nic would come on the set and explain, 'Here's what's going on in this scene and what led you up to this.' And that's it. And that's what you get and that's what you work with. It was quite the experience."

Mackenzie says he loved working alongside the star-studded cast, which also includes Rachel McAdams, Colin Farrell, and Taylor Kitsch.

"Vince is awesome. He's a great guy to work with. Family guy, goofball -- but as soon as they call action he's not a goofball anymore. He's got the ability to switch on and switch off," said Mackenzie.

Now three episodes in, viewers are getting a better sense of how character development and the plot of the series, which follows California authorities investigating the bizarre murder of Caspere. Critics, so far, are mixed on season 2; some say it's not nearly as strong as season 1, which had a completely different story line and cast, with Matthew McConaughey and Woody Harrelson as the leads.

"Everybody's going to want to compare this season to the first season. There's no comparison. Except for the title," said Mackenzie.

The secrecy continues for Mackenzie, who says he's watching most of the season unfold with the rest of us. Even he hasn't seen all of the episodes.

Meanwhile, he's keeping busy on the acting front and will soon appear in an episode of TNT's "Murder in the First," as well as the horror flick, "Daylight's End." He's also behind a Kickstarter campaign for "The Unwanted," a new supernatural thriller, written by Destin Pfaff, the same filmmaker behind 2012's "Sushi Girl."

Episode 4 of "True Detective" season 2 airs Sunday at 9 p.m. ET on HBO.