You've probably heard about the beginning of this story. As the "ringleader" of the West Memphis Three, Echols was wrongfully accused and convicted of the gruesome murders of three little boys, and given a death sentence at the age of 18. Eighteen years and several appeals later, he was released from prison thanks to a tricky plea bargain that allowed him and the other two members of the West Memphis Three to plead guilty but maintain their innocence. Written in an easy conversational manner, Life After Death is Echols’ memoir of life on death row.
Echols does not go into the details of the ridiculous trial that landed him on death row or the multitude of appeals on his behalf, other than to say that he was in constant disbelief at the injustice of the situation. So if a detailed recounting of the crime and trial is what you're seeking, I'd suggest Mara Leveritt's excellent The Devil's Knot. Echols' memoir is not that kind of book, but it's still fantastic--at times tough to read, at others, it's funny and even beautiful.