After taking the quest, map travel to Rata Sum and exit into Magus Stones from there. Follow the quest marker to Naveed (#1 on the map), who will lay out his plan. The quest will then update, and the marker moves to where a party of White Mantle are located (#2 on the map). They will be non-hostile towards the party regardless of any character's past actions against the White Mantle (Spoiler warning - see Prophecies storyline for more detail). After speaking with them, they will follow the party back towards where Naveed is waiting, they will not assist the party in any fights nor get attacked.