Katie Holmes films racy love scene with rumored boyfriend Luke Kirby

Photographers spotted Katie Holmes and her co-star Luke Kirby filming a steaming outdoor love scene on the set of their new film, "Mania Days."

In the scene, the 34-year-old actress wears a pale blue bra while her 34-year-old Canadian co-star goes shirtless. (Check out the photos over at E! Online.)

The New York Daily News has details about the pair's attempts to keep their supposed relationship private. One source said that Holmes and Kirby acted strangely when people saw them together in the East Village.

She bolted, jumped in the back of a cab and lied down in the back seat. ... Meanwhile Luke walked to a falafel place on MacDougal St. and was texting furiously and looking around. All of a sudden, Katie comes down the street. Normal people don’t act like this.

"Mania Days," produced by Spike Lee, is the story of two manic depressives who start a relationship after meeting in a psychiatric hospital.

Holmes and Tom Cruise finalized their divorce in July 2012. Cruise recently said that Holmes' decision to divorce him came as a surprise.

"I did not expect that," he said. "To be 50 and have experiences and think you have everything under control, and then it hits you -- that's what life is ... Life is tragicomic. You need a certain sense of humor."