Exclusive: Watch Hilary Duff's Hot Teenage Mess Get Rebuffed in Clip from Stay Cool

Hilary Duff may have seen her planned screen turn as Bonnie Parker nixed due to pregnancy, but the erstwhile Lizzie Maguire will soon appear in the Polish brothers ensemble comedy Stay Cool. The 2009 Tribeca entry concerns a thirtysomething novelist (Mark Polish) who returns to his Sacramento hometown only to be confronted with the colorful ex-flames and friends still living there and the hot-to-trot high school senior (Duff) trying to jump his bones. Get a first look at Duff's would-be teen seductress (and her failed attempt at seduction) in Movieline's exclusive clip.

Duff was 20 when Stay Cool was filmed, and the indie comedy falls smack dab in the middle of a period in which the former tween star seemed to be making very deliberate choices for more mature fare -- even if most of said roles came playing promiscuous teen jail bait in one film after another (see: War, Inc., What Goes Up). Here Duff demonstrates some developing acting chops as high schooler Shasta O'Neil, who unsuccessfully tries to mack on older man Henry McCarthy (Polish) in front of everyone at a pool party.

The official synopsis for Stay Cool, which features the most random cast assemblage you'll see all year:

From Initiate Productions comes raucous and romantic comedy about one man's return home for the commencement speech of a lifetime.

Henry McCarthy (MARK POLISH), the 30-something author of the popular 80s-themed novel How Lionel Got Me Laid, returns to his suburban hometown of Sacramento to deliver the commencement speech at his former high school. Despite his success as an author Henry's return home has sparked all of the youthful dreams, desires and particularly disappointments he's never quite gotten over, specifically his unrequited affection for the girl who is now the local pharmacist: the elusive Scarlet Smith (WINONA RYDER).

Between run-ins with the outcast friends he left behind Big Girl (SEAN ASTIN) and Wino (JOSH HOLLOWAY), the school principal (CHEVY CHASE) and a seductive senior, Shasta O'Neil (HILARY DUFF) who clearly has the hots for him, Henry is sent spinning through a time warp that incites all the old emotions and challenges of the world he grew up in. Teetering between unsettling memories of his teenage past and his all too uncertain adult future, Henry can only hope to "Stay Cool" and make it, once again, to graduation day.

Stay Cool, directed by Ted Smith and starring Mark Polish, Winona Ryder, Sean Astin, Hilary Duff, Josh Holloway, Jon Cryer and Chevy Chase, will open in select theaters on September 16.