Books like Understanding Ethics
Noel Preston
Understanding Ethics is 238 pages, about 4 hours 22 minutes at 250 words a minute.
6 books to read next
How long each takes
Animal Liberation 5.9 h Moral Thinking Fast and Slow 2.0 h 
Practical Ethics 7.3 h 
Ethics and Technology 7.3 h 
The Sovereignty of Good 2.0 h 
How to Observe 4.6 h Bar height shows length. Estimated at 250 words a minute.