Books like The Mystery Horse
Gertrude Chandler Warner, Charles Tang
The Mystery Horse is 121 pages, about 2 hours 13 minutes at 250 words a minute.
12 books to read next
How long each takes
Into the Gauntlet 5.7 h 
Paint The Wind 6.0 h 
Tales of a Fourth Grade Nothing 2.2 h 
Dark Places 6.8 h 
The Maze of Bones 4.1 h 
The Viper's Nest 3.2 h 
Strawberry Girl 3.5 h 
Harris and Me 2.9 h 
Eight Cousins 4.7 h 
The Heaven Shop 3.8 h 
Flambards 4.1 h 
Five Little Peppers and How They Grew 4.4 h Bar height shows length. Estimated at 250 words a minute.