Karen was a reporter with the East Africa Standard when the investigators first met her on the train journey from Mombasa to Nairobi. She later turned up at the Norfolk Hotel to interview them about some unusual arson attacks, and accompanied them on their outing to Endicott's Game Lodge.
She was a passenger in Harry's plane when it crashed, and was captured by cultists, but rescued by the investigators in time to assist them in their adventures at the Mountain Of The Black Wind.
When the investigators left Kenya for the States, Karen decided to remain in Nairobi. However she later contacted them and rejoined the party in Hong Kong. From there she accompanied them to Shanghai.
Karen seemed to have developed some unusual habits since the investigators first met her, but remained a trustworthy companion, still cool under pressure and a very good shot with a rifle!
After returning from Gray Dragon Island, Karen adopted a new hairstyle and wardrobe, and developed a fondness for cigars and malt whisky . It's unclear at present what (if anything) the significance of this is.
Following her pregnancy, which was announced as the investigators crossed the Great Sandy Desert on 23 May 1926 Karen gave birth to a healthy pair of twins, George and Abigail. It's still unclear who the father is.
Since returning to Boston in March, "Mrs Hayes" has been staying with Mr Bryant and his household. She's currently supporting herself by acting as Mr Bryant's secretary and writing a regular "African Experiences" column for the Boston Herald. Recently she's been thinking of writing a book...