No Air in Space — Madeline James

The idyllic family life is a concept foreign to identical twins, Nikki and Taylin Radakovich. With a coolly-sadistic father as secretive as he is abusive, turning 18 for them represents more than just becoming fledgling adults. It signifies the freedom to escape the hell theyd been forced to call home. However, until time allows them their wish, theyre determined to make it through in the only way they know how, continuing a bond society deems inappropriate and one thats set to become the target of their small world as well as the root of their emotional upheaval.