Credit: Donato Sardella/WireImage; Dimitrios Kambouris/FilmMagic

Don't let Tom Cruise know about this!

Katie Holmes will romance Chace Crawford in the upcoming romantic-comedy Responsible Adults. According to Deadline, Holmes, 32, will play a woman who seduces a charming younger man played by Crawford, 25. 

In the film, Holmes's character is 30 and Chace's is 22; their relationship blossoms until they realize they've already met -- 15 years ago when she was his babysitter!

Kirk D'Amico, CEO of Myriad Pictures, said Holmes and Crawford "are appealing actors around the world." Casting for other characters has not been announced, and shooting is expected to begin in late 2011.