"I got back on a Thursday from hiking in Yosemite," Knepper told us when we talked on the phone in advance of the episode. "I had just finished a gig on 'Hawaii 5-0,' and then I get back the next day, and, 'You're getting on a plane, and we're filming all of your stuff on Saturday. Everything. The entire episode. Please get up here quickly, because we've got to figure out costume.' "
Knepper is no stranger to the breakneck pace of television. You may not necessarily know his name, but he's appeared in over 100 movies and TV shows in the past three decades, including regular stints on "Prison Break," "Heroes" and an upcoming gig as the mysterious Antonius in "The Hunger Games: Mockingjay — Part 1" and "Part 2."
But even for a seasoned professional, the pace of "Arrow" was a little bit insane. So crazy, he didn't even get to meet series star Stephen Amell.
"I never even got to see him!" Knepper said, laughing. "I was shooting the pilot for 'Cult' when they were shooting the pilot for 'Arrow,' and we still haven't met. I worked with Caity [Lotz] and Emily [Bett Rickards]. We did the final climactic moment with these two ladies, which was very welcoming. They knew my work from 'Prison Break,' and commiserated with me. 'Well, you've got a lot to do.' "
In fact, what made the rapid speed of shooting bearable was what Knepper credits as the extreme professionalism of the crew, some of whom he's worked with on previous Vancouver based productions.
"I never felt with 'Arrow' that I was having one of those nightmares where I couldn't keep up," Knepper continued. "We just all worked as a team, with me all day inside this thing set up with all these computer screens, mission control kind of place. I don't know, I've been doing this for 30 years so I kind of get off on this sort of thing. How focused can we get here, and it went off without a hitch. It was great."
On "Time of Death," Knepper plays William Tockman, a.k.a. The Clock King. In the comics, the character is often depicted as a time traveling dandy, and even more recently with a giant clock for a face. So when Knepper heard he got the part, there may have been just a little bit of concern.
"My wife had the foresight to Google the character," Knepper recalled, "And boom, boom, boom, all these images come up of this DC character, and I went, 'Wow, you can go so many different directions with this guy.' And I said, 'Okay, I have to make it my own.' "
Even with the brisk pace of the production, Knepper did have time to talk to "Arrow" Executive Producer Marc Guggenheim, so he wouldn't be going into the role blind.
"I called him up and said, 'So when you put these characters in there, do they come from the written character already, the DC character. Or do you make them up?" Knepper said. "How much do you apply what's really there in the history, and how much do you elaborate on your own?' And he said, 'Generally we create a character and then go looking for a [similar DC Comics] character and see if they exist.' "
Though Knepper was concerned fans would be upset with the changes, Guggenheim assured the actor that they were far more often pleased with the television tweaks to comics continuity. "What we ended up doing was a nice mixture of the comics, what was written before for Clock King, and them letting us go," Knepper noted.
He describes the character as "a little OCD," concerned with time and talking either too fast, or in staccato rhythms reminiscent of the "tick tock, tick tock," of a clock. Knepper was also pleased with his character's motivation, which he found far more three-dimensional than most done-in-one guest turns. In this version, Tockman only has a limited amount of time to rob a bank to get the money to pay for his dying sister's operation.
"This guy had a real purpose in why he was doing it, for the sake of his sister," Knepper added.
And as for returning to the show? Though we'll find out Tockman's fate when "Time of Death" airs, as long as he survives Knepper would be happy to come back.
"The word was when I shot it that they were very happy with me, so it's a mutual feeling," Knepper said. "I hope that they will continue making him a worthy opponent."
First though, Knepper has to take on the role of Antonius in the final two "Hunger Games" movies, a part he'll start filming in April. Though hopefully for this one, he has a little more time.
"I'll go over there in a month and it'll be another Clock King type thing," Knepper said, laughing. " 'By the way, you're shooting everything in one morning!' "
"Arrow" airs Wednesdays at 8 p.m. ET on The CW.