Ed Harris is joining Casey Affleck and Michelle Monaghan in Ben Affleck's new film, Gone, Baby, Gone for Miramax Films.

Harris will play a cop in the pic, says Variety, which centers on two private investigators hunting for an abducted 4-year-old in Boston's underworld.

Affleck based the script on the Dennis Lehane novel; production for Gone, Baby, Gone will begin next month in Boston.