Hilary Duff by Jason LaVeris/ WireImage.com
The mercury may be climbing, but that's not phasing Hilary Duff, who has plans to Stay Cool this summer by shooting a new comedy from the Polish brothers.

Duff joins the cast that already includes Winona Ryder, Mark Polish, Sean Astin, Chevy Chase and Jon Cryer. According to the Hollywood Reporter, Cool follows Polish, a successful author who must face a former crush (Ryder) when he returns home to make a graduation speech at his high school. Duff plays Shasta O'Neil, a sassy senior who becomes flirty and invites Polish to the prom.

Mark Polish wrote the movie with his brother Michael, who will direct the flick. Shooting is scheduled to begin in July. Does this comedy sound Cool to you? - Adam Bryant