So many films take tortuous years of dealmaking to reach the screen that it's reassuring to find a project that came together practically overnight.

Such is the case with Law Abiding Citizen, a psychological thriller starring Jamie Foxx and Gerard Butler opening Friday via Overture Films.

It was a call from Jamie Foxx, said director F. Gary Gray (The Italian Job), when asked how he got involved. We've always wanted to work with each other. He told me it was a project he thought I should strongly consider.

After Foxx called last October, Gray read Kurt Wimmer's screenplay. I loved the concept and thought it was really unique.

Next step: Meeting with Mark Gill, the CEO of indie production company Film Department, and Citizen's producers, including Lucas Foster (Mr. and Mrs. Smith).

Gray (explaining): The rest is history. We had a lot of meetings in-between. I put together my visions for the material. It was relatively simple.

Butler plays the title's upstanding citizen who's terrorizing Philadelphia from behind prison bars to avenge his family's murder 10 years ago. Foxx is the assistant D.A. who gave one killer a plea bargain deal and now finds his own life in danger.

With most movies it's very easy to predict who the good guy is and who the bad guy is and you can also predict what they're going to do, Gray observed. With this movie, that's not the case.

What you can count on is that there's plenty of action. Getting it all on film kept Gray and his team busy shooting in Philly for 48 chilly days from mid-January through March.

One of Citizen's most challenging set pieces takes place in a cemetery where a weaponized bomb disposal robot attacks a security convoy.

Two weeks before shooting the scene Gray realized it needed major changes.

Gray (calling Foster): The way it's written doesn't work for me. We need a way to amp it up and make it more modern.

As written the scene hinged on a rocket launcher, which Gray felt was pretty old school. It fit more in a movie from the '80s than in 2009.

The goal: Turn it into something cooler without changing the movie's tone.

Gray's plan: Create a killer robot in place of the rocket launcher.

I felt it was smarter and in step with the character, who's an ex-spy.

Foster (to Gray): We only have two weeks and we have to get the Department of Defense involved and get clearances. I don't know if we can make that happen.

Foster (after Gray didn't take his first no): Let me see what I can make happen.

Gray (happily): Everyone put everything into making this work for me and in two weeks we found a robot from the Philadelphia Police Department. We disassembled it and rebuilt a weaponized version.

Shooting all that action kept him on his toes: We had seven cameras out there because when you're shooting on a practical location you don't have the time to spread it out over a week.

And they won't let you blow up an SUV 16 times when you're working in the middle of a working cemetery.

Experience always helps. I went through the same thing with 'The Italian Job' where we were shooting a boat chase in the canals of Venice.

He learned a lot in Italy from months of planning and storyboarding and coordinating and having to really be careful about the wake the boats would create so there was no damage to any of the palazzos.

Gray's worst challenge was Philly's winter weather when you're shooting interiors in a prison that's actually a functioning prison and it's 30 degrees inside. The actors had to wear thermals under their costumes.

Although Gray would only characterize his indie budget as being mid-size, he noted there were great incentives for filming in Philadelphia.

I was going for a neo-noir feel and Philadelphia was perfect for that. When you look at noir films there are specific elements I thought would give this movie a certain tone and mood. I took full advantage of the bridges and smoke stacks and the City Hall with its historic architecture.