So. I can't remember the address. And I can't find a website or anything in Urbanspoon. Probably best to have a walk around and see if anyone can find it again. Start from Argyle Street. From memory you walk through the archway, down a long set of stairs, and along a few backstreets. Look for the old abbey/church with the black double doors. You can't miss them.
[Update: story continues in The Confession.]