John Travis Green 
The Cousin Seven: Beasts of Summer Hallow [EPUB ebook] 

A group of seven inseparable, rambunctious teenagers, known to their small hometown as “The Cousin Seven”, witness something so horrifying that they, themselves, cannot even explain. An innocent summer graduation trip, to a family cabin deep in the hill country of North East Texas, ends up in the mysterious loss of one of their friends. Fifteen years later, the remaining group of friends decide to find answers to their haunting memories. They set out on a mission, to go back to the cabin that robbed them of their childhood and has now claimed the lives of two of their lifelong friend’s.