Katie Holmes was spotted on the New York City set of her upcoming film "Mania Days" straddling her rumored new boyfriend Luke Kirby. Holmes was only wearing a bra as she passionately kissed her co-star.

Of course this was all in the name of  production as the two shot a steamy love scene for the upcoming flick. According to the Daily Mail the actress embraced Kirby and as her messy brunette hair spilled on to her shoulders she went in for a kiss.

At one point Kirby cradled Holmes' head against his chest as she pulled him in close for a amorous hug.

Following the scene the actress was all smiles as she sat with her co-star and chatted it up during their break.

[To see photos of Katie Holmes' and Luke Kirby's steamy love scene click HERE]

The Daily Mail reported that "The pair were spotted smiling after the choreographed make out session, with the actress even puckering her lips as she appeared to banter with the hunky thespian."

The co-stars have been rumored to be dating ever since they were spotted in early May, when Kirby was seen taking Holmes to dinner and the two appeared to be having a good time.

Apparently something is going on because the star who can usually be spotted in her Chelsea neighborhood has rarely been seen over the past month.

A source told the New York Daily News "The last month you rarely see her anymore.

"Whatever she's trying to hide I don't know, but she's not going in the main entrance [of her building] any more."

Holmes and Kirby were nearly holding hands when they were spotted earlier this month strolling the streets of NYC together.

The film which is set to be released in 2014 stars the actress as a manic depressive poet who gets pregnant by a maniac depressive rapper.

The movie is said to bring out the beauty and horror of their shared condition.