'The Vampire Diaries' Nina Dobrev: Is Katherine coming out of the tomb?

New episode stills from upcoming "The Vampire Diaries" episode "The House Guest" have us asking that question again: Elena or Katherine?

Usually we differentiate between the two based on hair - Katherine's is curly, Elena's is straight - and, of course, their necklaces. Katherine wears a lapis lazuli stone around her neck so that she has the ability to walk in the sun, whereas Elena wears a vervain locket to keep her safe from vampire compulsion.

So is Katherine due for a jailbreak? Executive producer Julie Plec hesitates to spill any details of her great escape. "If Katherine has her way, absolutely, she'll be getting out of that tomb," Plec says. " It's all going to come down to how crafty she can be."

In the new photos, Nina Dobrev isn't wearing a necklace -- but she is wearing a very Katherine-like smirk. What are the chances that Katherine may have found her way out of the tomb and into the Salvatore house as the house guest in question?

Chances are good. Even though she's dressed up in some very Elena-like clothes, the glass of bourbon gives Katherine away. While Elena may curl up with a glass of wine on the couch on occasion, we've yet to see her go for the hard stuff casually. As for the missing necklace, it's a heck of a lot easier to keep our vixen vamp under house arrest when she can't go out in the sun.

We know one person who is thrilled to have Katherine out of the tomb and all cleaned up -- Nina Dobrev herself. Zap2it sat down with Dobrev on her most recent trip to Los Angeles, and she shared the woes of Katherine's incarceration.

"Katherine-slash-I have been dirty and dusty for a very long time," she laughs. "The weird thing is having to put dirt in your hair and tease your hair and make it look dirty after you've just washed it, for all those scenes."

You'd think that as the star of a CW show, Dobrev would get the glam treatment every day at work, but that's not the case as long as Katherine's below ground. "Katherine's getting progressively dirtier and dirtier," Dobrev says.

The make-up artists paint shadows under her eyes and in the hollows of her cheeks to make her look sunken in and thinner. Plus, Katherine's foundation is three shades lighter than Elena's. They make sure her arms and face are dusty and dirty, and they don't skimp when it comes to gunking up her hair.

"The only part that bugs me is when I wash my hair and then I have to put dirt in it. That's the only thing. I just washed it! I'm a girl!" she laughs. "Otherwise, I like to get down and dirty and really messy."

So you can bet Dobrev is looking forward to Katherine taking a nice long bath when she climbs out of that cave. "She's plotting her way out," she says. "She's a woman who likes to be in control and when she's not, she's not happy."