Oftentimes authors whose books are adapted into movies are left to sit at home and simmer as directors make the rounds saying how their "reimagining" of the work was necessary to make it a better cinematic experience, blah, blah, blah, while every fan of the novel knows exactly how it was butchered.

Yet, here in front of me, in the same room, are two Scotsmen — director Jon S. Baird and author Irvine Welsh — contentedly discussing the book and movie versions of "Filth," with nary a hint of venom in the air. They sit there chuckling about the Shinjuku fembot bar they were drinking at the night before. What gives?

"It would have been easy to do this book really badly," says Welsh, "as a bad-behavior-type movie without any depth to the character." Indeed, Welsh's novel was optioned shortly after publication in 1998, but went through a decade of disputes and development hell before Welsh was introduced to Baird via a mutual friend. "He knew the book better than I did," says Welsh, who was convinced enough by Baird's passion for the project to get personally involved in pushing it through. Baird, however, jibes him, saying, "He just wanted a drinking partner, that's all."