by Jim Ridley
We saw Boston's Alloy Orchestra perform a few years ago at The Belcourt with Alfred Hitchcock's silent gem Blackmail. "Exciting" doesn't begin to describe Alloy's fusion of live musical accompaniment and silent cinema: the mood in the room was electric. If you missed the restored version of Fritz Lang's sci-fi masterpiece Metropolis a few months ago, tonight you can not only see the film but hear it accompanied by Alloy's furious live score — a show that has drawn full houses and ovations around the world. It's 7 p.m. tonight at The Belcourt, assuming any $20 tickets remain.