Emerine is in the mulbury caves. You can get there via Korg telling you about it, which he will eventually do amidst the discussion of Northcrest/Orc battles. (There's also a way to get there without Korg, but I don't know what it is).
You can then find it in the section of the cave-dungeon with the Emerine golems (They only show up in that one area).