Travel to Olafstead to speak with Valgar, then you can either exit and head east to see Lefsi, or if you have Central Transfer Chamber on your map, it will be quicker to start from there, through Battledepths. After talking to Lefsi, he is attacked by several waves, first of Vaettir, followed by Mindblade Spectres and Smite Crawlers, then Coldfire Nights and Stalking Nights, and finally Tortured Spirits. Eventually, the ghost of Gwen's mother, Sarah will appear and the pendant is charged with the spirit of family. Map back to Eye of the North, show the pendant to Thackeray, before entering the HoM to give it to Gwen.