She was portraying a young medical student about to perform an autopsy, and she was having trouble taking the moment seriously.

"That’s because the young man in question was a very alive human being who had been made to look dead," Heigl laughs. "And I had been chatting with him earlier that day. So it was kind of funny to have him lying on the table looking like the corpse."

But by the time that scene from Valentine ends, some distinctly unpleasant events have occurred. Now when Heigl watches it, she gets goose pimples all over because of what happens.

"It’s really scary. It really is."

Heigl, whose starring performance as a teen alien on Roswell has won her a TV following, made a previous foray into the horror genre in 1998 when she made Bride of Chucky. She was never able to take that movie seriously – when she was making it or afterwards. But she says Valentine, which arrives on screens Feb. 2, is a different proposition.

Valentine represents Warner Bros.’s attempt to see whether there’s still life in a genre that in earlier decades sparked the Nightmare on Elm Street, Friday the 13^th and Halloween cycles. The film is directed by Urban Legend’s Jamie Blanks and based on Tom Savage’s best-selling novel of the same name. It focuses on four young women (portrayed by Heigl, Marley Shelton, Denise Richards and Jessica Capshaw) who find themselves terrorized by a Valentine’s Day killer.

The 22-year-old beauty is on the line from her home in Los Angeles, chatting about her career while trying to quiet the yapping of her three schnauzer dogs who "go insane" whenever the telephone rings.

She’s having a rare day off from Roswell, the series which has become a cult item since its premiere last season. It’s also proved to be a major career boost for Heigl, who started working as a child model at the age of nine and made her feature film debut three years later in That Night.