Halldir's Cairn is located just south of the Dark Brotherhood Sanctuary. Inside, there are numerous mushrooms and a strange cairn surrounded by dead bodies from which emanates a magic beam. Next to the pile of stones is a pedestal with Agrius's Journal and the Key to Halldir's Crypt.
Along the way through the cave, the Dragonborn is attacked by 10 subjugated ghosts and a few draugrs.
 Halldir's Crypt
Here, the Dragonborn confronts Halldir.
 Items of Note
- 70+ mushrooms: Blisterwort, Imp Stool, Namira's Rot, White Cap.
- Black Soul Gem, many ruined books, Scaled Helmet, several potions, Steel Shield
- On a pedestal: Spell Tome: Raise Zombie
- In a wall niche, under a stone serpent head (in the puzzle room): Elven Mace
- In a flat pool of water: Potion of Vigorous Healing
- In the room previously seen through a crack in the rock wall: Ebony Warhammer (L37), Grand Soul Gem.
- In Halldir's chamber: Dwarven War Axe, Glass Helmet, Glass Armor, chest ~2130 value (L37) also contained Rjorn's Drum.
- Halldir drops Halldir's Staff.