Who ya gonna call? The answer is "all of your friends," because the Ghostbusters are putting the proton packs back on for a new case.

In an exclusive interview with franchise director Ivan Reitman, sources say that Bill Murray has finally agreed to reprise the character of Dr. Peter Venkman and team up with Dan Aykroyd, Ernie Hudson and Harold Ramis for not just one, but two 'Ghostbusters' adventures. They are set to be filmed concurrently and released back-to-back for Christmas 2012 and Christmas 2013.

The development of 'Ghostbusters 3' has been brewing for years, but news about the project really started to heat up in the past 12 months. For quite some time, the delay in getting the movie made has been Murray, who was vocal in his displeasure with the previous draft of the screenplay written by Gene Stupnitsky and Lee Eisenberg. But back in the fall, Dan Aykroyd told Vanity Fair that he had taken over scripting, and then last month, while promoting 'No Strings Attached,' Reitman revealed that Murray had seen the newest draft, and going forward with a new 'Ghostbusters' installment would come down to his approval.