Review: Chernobyl: History of a Tragedy by Serhii Plokhy
If you ever want to truly understand what happened, this is probably the most comprehensive book you will ever find on the topic. The author truly 'gets' his subject and explains it carefully to the reader, so that it can be understood and appreciated by those of us who don't have a degree in nuclear physics (i.e. most people.) Accounts of what happened to various people on the frontline of the tragedy are told in a dramatic style.
There's no doubt that what unfolded was a tragedy (as the title suggests,) and human side of things was very hard to read. And the most frightening part of all is just how easily something similar could occur in another part of the world, where the need to appear advanced and high tech to fuel a political agenda outweighs safety and practicality.
The detail in Chernobyl: History of a Tragedy is so rich that it makes for a compelling read.