The Circular Staircase
Mary Roberts Rinehart
<p><i><b>The Circular Staircase</b></i> is a mystery novel by American writer Mary Roberts Rinehart.
 The story follows dowager Rachel Innes as she thwarts a series of 
strange crimes at a summer house she has rented with her niece and 
nephew. The novel was Rinehart's first bestseller and established her as
 one of the era's most popular writers. The story was serialized in <i>All-Story</i> for five issues starting with the November 1907 issue, then published in book form by Bobbs-Merrill in 1908.
</p><p>Rinehart was inspired to write the novel after a visit to Melrose, a Gothic Revival castle in Northern Virginia.[1]
</p><i>The Circular Staircase</i> pioneered what became known as the "had I but known"
 school of mystery writing, which often feature female protagonists and 
narrators who foreshadow impending danger and plot developments by 
reflecting on what they might have done differently. Rinehart employed 
this formula in many of her later works, and it inspired dozens of 
subsequent stories