Plus, "Sunny in Philadelphia" co-star joins "Leap Year"

One movie star is going back to her crusading ways, and another is getting silly.

Rachel Weisz will headline indie drama "The Whistleblower," according to Variety.

The actress, whose do-gooder character's murder spurred the plot of 2005's "The Constant Gardener," will star as an American policewoman out to expose a sex-for-hire plot in Bosnia.

Weisz, 38, stars this year in "The Lovely Bones."

On a lighter note, "It's Always Sunny in Philadelphia" star Kaitlin Olson has joined the cast of "Leap Year," according to The Hollywood Reporter.

Olson, who plays Sweet Dee on "Sunny," will play sister to Amy Adams' character, who tries to find her boyfriend in Ireland so she can propose on Leap Year Day.