Fighting over Bridget Moynahan in the new film

Heather Graham and Tom Cavanaugh were the perfect couple - they knew each other so well, they were the best of friends; the only problem - they're brother and sister.

The two actors star in the new film, Gray Matters from writer/director Sue Kramer. What makes this even a trickier story is on the night before Tom is going to get married to Bridget Moynahan, Heather steals her away from him; it's a true sibling rivalry romantic comedy.

The cast, besides the three leads also packs a punch, including Molly Shannon, Alan Cumming, and Sissy Spacek. "I really liked working with Molly because Molly is a good friend of mine so it was cool that we got to play friends," notes Heather. "Tom is really fun; he's like, joke, joke, joke. He's just really a goofball and he let me physically beat up on him which was really fun. And Bridget is a really cool, not actressy; she's down to earth and really great, and Alan is super charming and funny and I felt really honored to be working with them. Sissy Spacek is really a legend so it was really cool to have a few scenes with her and I've admired her for so long. I think she's one of the best actresses."

For Tom, getting beaten up was just part of the process with Heather. "Basically, very early on in our time together she started slugging me during scenes; the first time she was like, 'I'm so sorry,' and I was like, 'Girl you can't hurt me.' Then, it all became a thing whether she could actually lay the beating on the boy, so a lot of our scenes and a lot of the more violent stuff actually didn't end up on camera because they're like 'can you tone it down a bit because this isn't like Ultimate Fighting but we had a lot of that going on. Ultimately, that contributes to the brother sister relationship a little bit; makes it seem a little more real on screen, and she loved it"

Gray Matters is a role we haven't seen Heather in before, and that's one reason she wanted to do it. "When I read the script, I really liked the feeling I got at the end of it; I liked what it was about, that it was about someone kind of learning to accept themselves for who they are and celebrating who they are. I kind of felt like I could relate to that even though I hadn't gone through the exact same thing but it's hard to really learn about yourself and to accept all the different parts of yourself. I thought it was a very happy story. There's that moment where Alan and I are on top of the building and it's that beautiful view of New York and she shows the Empire State Building and I felt when I was watching it, I just thought that having your life be a backdrop to your life and you go through all these different things and it's what your surroundings. It was weird, I don't even know what I'm saying but it's a backdrop to your life and I could relate to all the things that have happened to me when I've been in New York and looking at it and it's this beautiful backdrop to your life, I was looking at it thinking it was this beautiful backdrop."

Sue gave all her actors free range on the script, so Tom, who's well known for adlibbing his lines, was very much in his prime. "Yeah, I think sometimes you get that with a first time director and other times you don't - in this case we certainly did. The old turf ship for her was not the most important, getting the story right was; we had a lot of room to play around and Sue was gracious enough to allow her actors to kind of get that kind of playfulness out on screen without worrying too much whether we were sticking to exactly what was in the script. That's an indulgent way of kind of describing it and I don't mean to be that way but yeah we had the freedom to goof around the way brothers and sisters do."

And Heather echoed Tom's thoughts on Sue. "I think she was very passionate and I felt she had a vision; as she was directing me, she was very specific about what she wanted. That made me feel good because I felt like she could see the end product and we weren't just screwing around doing whatever; she really knew what she wanted and I felt she had passion for me playing the part, too which is good for an actor. If you're feeling a bit insecure and you're trying something new, I've never done it but just to feel her enthusiasm and passion made me feel a lot more confident."

Sue wrote Gray Matters based on her sister's life; Tom kind of plays that role. With his writer and director so passionate about this part, Tom could only soak up her energy. "Her sister, Carolyn, she'd be on set a lot of the time; she's been a huge supporter of the movie and I think she's extremely proud and happy for Sue. As you know, this is a small movie but any movie that gets made, any script that gets written is an accomplishment. Any movie that gets made and ends up in a position where people are coming to talk about it, it's not a small thing. Whether the movie does anything in terms of viewer-ship is almost beside the point. It's an accomplishment already. Carolyn is extremely proud of Sue and Sue is extremely proud of Carolyn and the end of our last shooting day there was a lot of tears and a lot of raising of glasses to the 2 of them. As an actor, all you can ask for is that you want to be able to do the parts that go across the spectrum - good guys, bad guys, what have you."

Check out Tom, Heather, and Bridget in Gray Matters in theaters February 23rd; it's rated PG-13.