Books like The Sierra Gold Mystery
Carolyn Keene
The Sierra Gold Mystery is 192 pages, about 3 hours 31 minutes at 250 words a minute.
6 books to read next
How long each takes
Arsenic For Tea 6.6 h 
13 Clues for Miss Marple 4.0 h 
The Haunted Attic 3.9 h 
The Vanishing Shadow 4.0 h 
The Mysterious Half Cat 4.0 h 
Riddle of the Double Ring 4.0 h Bar height shows length. Estimated at 250 words a minute.