Bring 15 Skeletal Fragments to Alchemist Arbington at Chillwind Point, Western Plaguelands.
The key to Scholomance is called a Skeleton Key. It must be forged from the remains of a skeleton - several actually - and hardened by only the strongest of metals within a suitable mold. A signet of power from a being who naturally can open the portal to Scholomance will make the key ultimately function.
First thing's first though, [player]. We'll need skeletal fragments for the key's forging. Skeletons inside Andorhal should yield what we need, but the ones outside the walls might work too.