Brittany Snow knows what lies behind the mask of the infamous assailant known as “The Carver” on FX’s plastic-surgery melodrama “Nip/Tuck,” whose identity will be revealed in the show’s two-hour finale, airing at 9 p.m. today on Sunflower Broadband channel 56.

But she’s not telling.

“All I can say is, you won’t be disappointed,” Snow says. “That’s what I can say. The final episode is so brilliant. I have my friends bribing me and paying me and wanting to take me out, and I’m like, ‘No, I can’t even tell you, because I won’t be able to explain it as good as it is.’ It’s amazing. I think people are going to be really impressed.”

Word on the street has it that even the most ardent “Nip/Tuck” fans may not be able to guess. “It isn’t (guessable),” Snow says, “but it all makes sense. It’s so perfect.”

Snow has had a recurring role this season as Ariel, the new girlfriend of perpetually troubled teen Matt McNamara (John C. Hensley), who was raised by plastic surgeon Dr. Sean McNamara (Dylan Walsh), but is actually the biological son of his partner and best pal, Dr. Christian Troy (Julian McMahon).

The role has been a revelation for Snow’s fans, who are used to seeing her as the apple-cheeked, wholesome Meg on NBC’s “American Dreams.” As Ariel, the loyal daughter of a white supremacist (Brian Kerwin), Snow donned black clothes and eyeliner, sported Teutonic jewelry and spouted neo-Nazi slogans.

Brittany Snow

“It’s actually the most rewarding role I’ve had in a while,” Snow says. “This is the thing where I went to work every day just scared out of my mind because it’s so unlike me. What I found is it’s actually really sad. I do feel for the character.

“It’s not really her choice; it’s what she’s been brought up with. Ariel is trained to think this way. She loves her father so much, and she wants to do what he says. There’s definitely an underlying subtext storyline of her father being abusive. She’s scared that he will hurt her. The relationship is a very unhealthy one. They’re so enmeshed and involved with each other that she just goes with anything he says in fear of him not loving her.”

Now that the job is over, Snow hasn’t held on to Ariel’s viewpoints, but has kept a bit of her fashion sense.

“I took some of the black combat boots,” she says. “I’m pretty preppy in real life, so it can look really cute.”

Even though he tried to get Ariel help for her psychological problems in the most recent episode, Matt often has crossed moral and legal lines, even resorting to violence.

“The funny thing is,” Snow says, “John is just such a great guy, and he’s so unlike his character. He is such a sweetheart, the sweetest, most generous, most professional actor. Working with him was always fun and great. So to see his character, watching him on the show, was just, wow. I was blown away by him. He’s very cute.”

The relationship between Matt and Ariel rapidly became sexual, and that was another change for Snow.

“Considering that John and I became really good friends during the shooting, it was very easy,” she says. “We just made fun of each other. By the time we had the love scenes, I knew the crew, and I was comfortable. It’s really awkward, but you’ve got to do it. It was definitely something new for me, but it was something that I was definitely glad it was over with, when it was over.”