Devil and the Deep is the newest installment in Julie Ann Walker's Deep Six series. It is currently on pre-order status for it's July 5, 2016, release date.
On Ms. Walker's website, she offers the following description for Devil and the Deep.
Bran is a warrior through and through. He is as rock steady as they come when in the heat of battle. He has crack in his armour though - Maddy Powers. While he wants her, the secrets of his past press on him. His character is another fine example of why I love books by Julie Ann Walker. Her heroes are very strong and able to fight the battles they face without blinking an eye. Yet, she gives up glimpses of the man behind the warrior. We see their inner struggles presented in a way that doesn't take away from their strength. In fact, their very weakness is a huge part of why they are so strong.
If you are looking to add to your summer reading list, this book is a must-have. Though a part of a series, Ms. Walker writes her books in a way that they can be stand-alone. You never feel lost if you read the books out of order.