You can get this quest by visiting Hillgrund’s Tomb, which is located east of Whiterun (it’s a crypt just southeast of Valtheim Towers). It’s easy to find on your way to Ivarstead. Once you’re there, you’ll run into a Nord named Golldir who will ask for your help in taking out a necromancer named Vals Veran, who is defiling the tomb. Agree to help to start the quest.
Golldir will be your follower here. Head inside and lead the way. Down the stairs is a wooden door in front of you. It’s got a mace trap behind it. Two Draugr will come up from below. Kill them and head down. The next door on the right has a Draugr standing up in a recession, playing dead, so kill him and kill two more Draugr that come up from below before heading down. There’s a chest down here that you can loot (Golldir will give you some shit about it, but he’ll let you). Further on you’ll find Aunt Agna! The doors to the main chamber are barred as well, forcing us to go further down.
Head down and kill two Draugr before looting the chest at the dead end. Take the door to continue and kill the Draugr in the recession before more come for you to kill. At the intersection go right for a chest, then left (watch out for a floor trap) to continue. You’ll fight more waking up Draugr and a giant spider in a wide open room before going down into a dead end with 4-5 Draugr to kill. After you’ve killed them all, Golldir will mention that Agna told him "The Bear will show the way" and sure enough, near the icon of the bear is a chain! Pull it to open the path.
Go through the tomb and kill another Draugr and soon you’ll see the wide wooden doors. Before going in, pick a door on the right for a chest and several potions. Head inside now to face Vals. This will be a fight against him and several waves of Draugr. Take the Draugr out quickly and try and hurt Vals only to have him teleport away. You’ll have to keep doing this until you kill off Vals (i’m pretty sure he stops teleporting after the second time). Once you do, finish off whatever Draugr there are and then Golldir will stop you and thank you. As a reward, he will give you 1000 Gold pieces and a chest key. Continue on up to the iron door and beyond will be some Gold and several gems on a table as well as a BIG chest that you can unlock with the chest key.
When asking Golldir what he’ll do next, he’ll say he’s going to bury his aunt and then stay in the area. If you come back in 24 hours, he’ll be hanging around the entrance and, if you wish, will become your follower if you ask him