First Blood (Side Quest)
This quest begins inside the treasure room of the Bent Pyramid of Sneferu.
Investigate the ankh to begin. This whole area now becomes an investigation area. Start with the arrow by the wall.
By the arrow is a scarab wall that can be smashed open.
Inside, note the large stone sarcophagus, and the mummified heron at its feet.
Smash some pots in the corner to find that mask with the dagger run through it. One of the pots, of course, contains a cobra.
These clues give Bayek enough to understand what happened.
These insights complete the quest.