His Toy is Trusting Him - Mind Games, #4

Dr. Jacob White shattered Katelyn's unremarkable existence when he wields his hypnotic charm to lead her down a path of passion and control that she could never have imagined. But just as Katelyn feels she's found true love and fulfillment, Jacob drops a bombshell - Katelyn must pass a test to join a secret society, where hierarchy and control reach unimaginable levels, and failure means the end of their relationship as if he never existed. The emotional fallout from Jacob's revelation and the demands of the society force Katelyn to confront her deepest fears and desires.
As she grapples with the emotional fallout of his revelation and the demands of a secret society where hierarchy and control reach unimaginable levels, Katelyn must decide whether to take the ultimate risk for the love and power she's found. The bombshell revelation and fall out leaves her questioning everything she thought she's learned about desire and power.  But as she delves deeper into the secret society, Katelyn is forced to confront the true extent of its power and control.
She must decide whether to take the ultimate risk for the love and power she's found, or to opt for the safety of the life she has always known. Will she trust him enough to risk everything for the love and power she's discovered, or will she choose the simple familiarity of her old life?  This is the final book is the continuation of His Toy Collection. It should be read after all the other books in the collection and not as a standalone.