Michelle Trachtenberg, best known for playing Buffy Summers’ sister on “Buffy the Vampire Slayer,” is set to join “Battlestar Galactica’s” Katee Sackhoff in TV producer/director Shawn Pillar’s feature film debut Sexy Evil Genius.

Sackhoff plays Nikki Franklyn, a psychotic sexy ex-con who murdered an old flame and is now out to execute a revenge plot that involves a group of her former lovers. No real info on Trachtenberg’s role, or that of costars Seth Green (“Buffy the Vampire Slayer”), William Baldwin (Flatliners), and Harold Perrineau Jr. (“LOST”).

Trachtenberg played Dawn Summers on Joss Whedon’s long-running hit series “Buffy the Vampire Slayer.” The pretty 25-year-old also starred as a sorority girl in Dimension Films’ 2006 remake of the 1974 Canadian slasher Black Christmas.

Sexy Evil Genius goes into production this week in Los Angeles.