Batman is being sought for the murder of ex-cons, cops, and Rachel Dawes. Commisioner Gordon meets a man named “StrongMan” who tells him he can capture Batman. Mr. Gordon grants him immunity for any crimes he many commit in capturing Batman. However Strongman is working for an underground mob. Due to the events that have unfolded Batman has fallen into a deep depression.

Is this a pseudo-sequel to The Dark Knight? Because the conflict for the character of Commissioner Gordon (ignoring the issue of rights as has been stated above) at the end of that story would not be that he needs to catch Batman, it's that he needs to make it LOOK like he's trying to catch Batman, even though he secretly knows Batman was the hero and so doesn't WANT to catch him.

Who is your protagonist? Gordon or Strongman? Does Batman's depression even factor into the other story at play here?

Im actually just using this idea for a practice script. Just a project i can work on for a few months. Any asistance u may have in beginning this story would be helpful!

All very valid comments above but the most valid is the ownership of these characters by DC. If you're just messing around, the above comments will really help you bring a solid logline together. If you're planning on writing this to sell, do some research first as I'd hate for you to invest all your time into a film you have no right to market out.

Good luck