James McAvoy and Jamie Bell are preparing for extreme depravity as they take on the lead roles in the adaptation of Irvine Welsh's underground novel, "Filth," according to The Playlist.

"Filth" follows the misadventures of Bruce Robertson (McAvoy), a sex-obsessed, drug-addicted and bigoted Scottish police officer whose latest murder investigation is continually sidetracked by his own bizarre and subversive shenanigans.

Robertson is (somewhat) watched over by his sidekick of sorts, Ray Lennox (Bell), and his boss, Bob Toal (Alan Cumming).

Sounds like a tale from the man who brought us "Trainspotting," for sure!

The long-gestating project, which has been through a constantly revolving door of different producers and directors over the past few years, looks to be finally coming together with Welsh on board as a co-producer and Jon S. Baird ("Cass") set to direct. Filming will commence in Jan. 2012.

James McAvoy will next be seen (heard) as the...