Mary Stewart’s Wikipedia page is here
There’s also a fascinating 2010  TV interview with her that you can watch.

Wikipedia credits her with having “developed the romantic mystery genre, featuring smart, adventurous heroines who could hold their own in dangerous situations.”

In a nutshell, she was the creator of Romantic Suspense.

Comments on Mary Stewart

From Sophie:

Credited with inventing the romantic suspense genre, Mary Stewart gave us resourceful heroines, driven into danger by circumstance and their own sense of responsibility plus some of the most compelling heroes going. Intelligent and beautifully written — nobody conjures up the sensuous pleasures of a landscape, climate and food as well as she does — these novels hit a nerve when they were published and, sixty years later, still do.

In the seventies she turned to Arthurian legend and wrote a masterly sequence of novels about Merlin.

From Joanna:

Can’t resist commenting that I was SO disappointed when I was digging out the Mary Stewart covers for the strip at the top of this page. The covers for the Merlin books are great but the others? In my opinion, there’s nothing even vaguely suspenseful about those covers for Nine Coaches Waiting and for Madam, Will You Talk?

Shame, I think. But you may disagree…?