By Mandi Bierly
Updated April 28, 2014 at 09:55 PM EDT

In the season 2 finale of The Following (Monday at 9 p.m. ET on Fox), twins Mark and Luke (Sam Underwood) turn the tables on Ryan Hardy (Kevin Bacon) and Joe Carroll (James Purefoy), who’ll have to work together to save Claire (Natalie Zea). Underwood has been so convincing in the roles, he’s been known to put fans on edge — including a security guard in the Time-Life Building when he popped by EW to take our Pop Culture Personality Test (watch it below): “He looked at me kinda like, ‘He’s a dodgy character who could have something dangerous in his bag’ as he was scanning my stuff,” Underwood says. “Then he looked up at me and went, ‘Are you…,’ and I said, ‘Yeah.’ As soon as he realized I play a psychopath serial killer twin, then he was fine with it.”

Underwood created two different playlists to help get him into each character as he was in hair and makeup. Top of the Luke mix? “‘Blurred Lines.’ He likes getting his dance on,” says the actor, who himself has been in dance school from the age of 5 and would love to don tap shoes again for a return to musical theater. And a track from Mark’s mix? “‘Radioactive’ by Imagine Dragons,” he says, “’cause it’s just so intense and it’s got a heavy beat.”

The actor is tight-lipped teasing the season finale: “I’m sure there’ll be a dinner scene, or something to do with cooking and a meal. Luke and Mark like to include food in their deviousness,” he joked to EW Radio. But in all seriousness, his costar Shawn Ashmore (whose Mike Weston may or may not have been shot in the penultimate episode) told EW there’ll be a different kind of cliffhanger than in season 1: “To me, it’s the kind of cliffhanger that makes you ask questions as opposed to [experience the] shock of seeing Claire laying there bleeding out. It will be interesting to see how people react,” Ashmore says. “All of a sudden, in the last-minute, your eyebrows go up. It’s not like, ‘Oh my god, this is crazy!’ To me, it’s a little more thought-provoking. It’s like a ball of yarn unwinding. It certainly made me raise my eyebrows and say, ‘Wow, this could be really interesting.'”