Amazon again offers its Prime members one early release Kindle eBook per month for free as part of its Kindle First Program. That's $5 under the list prices of these books, which are otherwise only available as preorders. Deal ends May 31.

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 The Butterfly Garden by Dot Hutchison, A House for Happy Mothers by Amulya Malladi, and We're All Damaged by Matthew Norman.