By Natalie Abrams
October 27, 2014 at 12:00 PM EDT
Cate Cameron/The CW

Barry Allen (Grant Gustin) has already put his powers to good use facing off against various metahumans since The Flash debuted, but he’ll meet his match during Tuesday’s episode when he goes toe-to-toe with famed DC Comics villain Captain Cold (Wentworth Miller).

What makes Cold such a daunting villain is that he isn’t actually a metahuman, but a notorious criminal who has long plagued Joe (Jesse L. Martin) and the CCPD, and suddenly finds himself the keeper of a Cold Gun from S.T.A.R. Labs. “Snart’s a master criminal at the top of his game, and I think he’s been there awhile and he’s a little bored, a little complacent,” Miller tells EW. “Then he meets The Flash, who upends everything. I think Snart appreciates that. On some level, I think he knows The Flash is going to keep him on his toes. Hence the need for new tricks, like the Cold Gun.”

A gun that can kill The Flash makes Barry “very nervous,” Gustin says. “Especially when he finds out where it came from and why. It’s very frustrating and concerning.”

The episode will culminate in an epic confrontation between hero and villain—though don’t expect Cold’s storyline to be wrapped up that quickly. “Snart’s formidable, of course, but long-term I suspect The Flash may have the upper hand,” Miller says. “For one thing, the show’s called The Flash. Also, The Flash has heart, which I believe counts for a lot in the comic book universe. If Snart has a heart, it’s buried deep.”

Captain Cold’s entrance comes at the worst time, though, as Arrow‘s Felicity (Emily Bett Rickards) ventures over from Starling City. “Barry has now become the Flash and he’s dealing with his double personality,” Rickards says. “She becomes a little bit of a guiding light. She’s able to give some insight and advice.”

“At first Caitlin is a little bit skeptical because she doesn’t want the whole world knowing Barry’s secret, but that’s something that she and Felicity have in common because they’re both protecting these guys,” teases Danielle Panabaker—though whether there’s a hint of jealousy on Caitlin’s part remains to be seen.

Speaking of love interests, Barry and Felicity will end up on what can only be described as an awkward double date with Iris (Candice Patton) and Eddie (Rick Cosnett). “There’s a trivia night going on at Jitters and I encourage Barry to bring Felicity along,” Patton teases. “It’s great to see them all interact with all the different personalities, and watching the relationship between Barry and Felicity and how awkward it is for Barry. Iris loves Felicity, she thinks nerd + nerd = love. ‘Hi, hot chick who likes the things you like. Date her!'”

But it might not be that easy. “They understand they’re going to working together for a while and there’s chemistry there,” Rickards says. “It’s interesting because they both live in different cities and they’re both dealing with life and death every day.”

The Flash airs Tuesdays at 8 p.m. ET on The CW.