Odor Most Foul (Side Quest)
In theory you get this one from the High Priest of Memphis, but it will populate on your map automatically when you reach the city.
Speak to the priests of Osiris at the quest marker to begin.
They'll spill out their troubles, and tell you to investigate on their behalf. Use Senu to find the cave entrance they mention, but you're practically standing on top of it already- it's a just a few dozen meters east, and down.
Enter the cave. There a number of branching paths in here, but ignore them. The passage you want is the wooden platform that will appear on your right.
There are enemies here- an archer and two swordsmen. Take them out.
Head west through a shattered wall, swimming with fumes.
Take a moment to kneel at the shrine and ask passage. It's the right thing to do.
Pass through the small square opening into the investigation area proper. Most of these clues are dead ends- the plot-advancer is the pooling, trickling blood in the far western corner.
Smash the wooden wall here to reveal cracked stone that you'll be able to climb through.
Light a torch to investigate the final marker, a pile of rotted bodies.
Knowing the source, fast travel the heck out of there and follow your marker to the wabet. A short cutscene will play as you enter, establishing your bona fides.
Here you can talk to people at every stage of the embalming process. Talk to them all if you're interested (and they are an entertaining bunch), but the plot-mover will be the guy stuffing the bodies with salt.
He'll tip you off about altered natron. Head out back to learn more.
Speak to the worker there, who spills a little more dirt (as it were) and directs you to warehouse where the mixture is stored.
This is in the far west of the city.
Bayek calls for caution as you approach,but there's no need. When you get close to the marker, you'll automatically trigger a cutscene in which you're roughing up the wabet supervisor.
He'll finger the bandits guarding the bad mix, and you can immediately use Senu to pinpoint the cave entrance under the Temple.
Up close, it's scarcely more than a shubbery'd crevice near the Temple's northwest corner.
Sneak in, and assassinate the bandits within.
There are only three- killing the last completes this mission.
