Open Library
Mystery
Every answer hides another question.

Sweet and Deadly
Charlaine Harris

The Viking Symbol Mystery
Franklin W. Dixon
Secret of Pirates' Hill
Franklin W. Dixon
Even the wicked
Lawrence Block
Cam Jansen and the Mystery of the Monster Movie
David A. Adler
Three Witnesses
Rex Stout
The Mars Room
Rachel Kushner
'Til Death
Evan Hunter
Darkstalker
Tui T. Sutherland
What's the worst that could happen?
Donald E. Westlake
Call After Midnight
Mignon Good Eberhart
The New Girl Friend and other stories of suspense
Ruth Rendell
Tunnel vision
Sara Paretsky
The Problem of Cell 13
Jacques Futrelle
The Murders of Richard III
Elizabeth Peters
The White Cottage Mystery
Margery Allingham
The Widening Gyre
Robert B. Parker
Cop Town
Karin Slaughter
Cam Jansen and the Mystery of the Television Dog
David A. Adler
The Pentagon Spy
Franklin W. Dixon