Need help finding title of horror movie? (Black Plague)?

I rented "One Missed Call" a couple of years ago, and I am trying to find one of the movies that they showed a preview for on the dvd. It was a movie where a group of researchers are in London, I think, and they're going underground or deeper into tunnels to try and study the Black Plague, or a disease like that. But then they find out that the Plague was caused by some demon/monster-type being that I'm pretty sure had a weird beak on it's face. I know this sounds weird, but if anybody could help, that'd be great!