Amazon again offers its Prime members one early-release Kindle eBook per month for free as part of its Kindle First Program. (It costs $1.99 for non-members who sign up for Kindle First monthly emails.) That's $5 under the list prices of these books, which are otherwise only available as preorders. Deal ends September 30.

Each month, you can choose from one of six new Kindle eBooks that are selected by Amazon's editors in advance of the books' official release dates. This month's titles include Michael Arntfield's "Mad City: The True Story of the Campus Murders That America Forgot", Marius Gabriel's The Designer, and Teresa Driscoll's I Am Watching You.