Fan Fare

It was a night of big revelations for “Knocked Up” star Katherine Heigl on Thursday.

First the natural  blonde actress debuted her new  look — as a brunette.

Then she showed off more  than she planned when the strap of her low-cut red dress broke off  as she was accepting an award as female star of the year at the ShoWest movie theater owners convention awards in Las Vegas.

And later she explained why she had colored her blonde tresses almost black. It’s all for a new movie role as  detective Stephanie Plum, the hero of Janet Evanovich’s best-selling novel s.

“She is a very specific kind of girl, so I just wanted to show the legion of fans that I will be your vision of Stephanie Plum. It’s important. I hate when my favorite books are made into films and they are just not what you expect,” Heigl, 31, told Us Magazine.

The movie is based on Evanovich’s novel “One for the Money” -- the first of 16 books in the Stephanie Plum mystery series about an unemployed New Jersey lingerie saleswoman who becomes a bounty hunter.

 ”I was pretty shocked at first…I was like, ‘wow, it’s dark, that’s not just brown, that’s black.’ It took me a good day and a half to totally embrace it, “she said of her new look.

But on the other big question on the minds of fans — whether or not she has left the TV medical drama “Grey’s Anatomy” –  Heigl was keeping mum. Heigl has been out of the show for most of this season after taking time off to care for her newly-adopted daughter Naleigh.

Stephanie Plum or not — should Heigl keep the new look, or go back to blonde?