Marjorie Simpkins is Kate De Vries's chaperone, who accompanies her on her many adventures. She's old-fashioned and disapproves of many things, often making prejudiced comments against them, such as Kate's romance with Matt, and of Nadira when she's on the Sagarmatha. She hates being in the air, but Kate manages to convince her to go with her and not tell Kate's parents by blackmailing her about her "flings" with men.