Mrs. Sedgewick attended the Council meeting held days after the big battle against the Endarkened. In the meeting she agreed with Lazlo Balogh, who raised the issue of the half-faerie, half-Shadowhunters Helen and Mark Blackthorn, believing the rumors that they were in fact traitors and in league with the faeries, and that they helped Sebastian easily penetrate the Los Angeles Institute. She questioned their loyalties and suspected that they would eventually betray the Nephilim, despite the objections of a few others. When Diana Wrayburn exclaimed that Helen was needed by her younger siblings, Sedgewick rebuffed this and told them that the Blackthorn children should be sent to the Academy or split up among various Institutes.
Mrs. Sedgewick is a dark-haired woman. At the meeting, she was seen with her hair piled on her head.
- City of Heavenly Fire (first and only appearance so far)