'THE BETWEEN': Sleepless in Miami

Let me start by writing that I don't know what to call the novel, The Between, by Tananarive Due. Is the story a  supernatural horror or fantasy within its contemporary setting? Is it a treatise on mental illness or sleep deprivation? Or is it something akin to time travel and alternate destinies with benign or malignant ghosts? Good questions and I think all those possibilities have their place in the story. 

South Floridian African-American power couple Hilton and Dede James with their two k...