Books like The Niagara Falls Mystery
Gertrude Chandler Warner
The Niagara Falls Mystery is 121 pages, about 2 hours 13 minutes at 250 words a minute.
12 books to read next
How long each takes
Amber Brown Goes Fourth 2.1 h 
On the Way Home 2.1 h 
Dark Places 6.8 h 
Locomotion 1.8 h 
The Bell Bandit 3.2 h 
The Tower Treasure 3.3 h 
Vespers Rising 4.1 h 
The Willoughbys 3.2 h 
Rainbow Valley 4.4 h 
The Door to Time 4.2 h 
Harvey's Hideout 45 min 
Then There Were Five 4.4 h Bar height shows length. Estimated at 250 words a minute.