Bring Him A Better Alibi. Nightlock Sins, #11

"The lock is not what keeps her. The lock is what proves she stayed."Criminal defense attorney Gemma Snow has spent four grueling years searching for her missing sister, Margaux. When a dead woman turns up in the exclusive, hidden Onyx nightclub wearing Margaux's silver medallion, Gemma is given a dangerous ultimatum. The club's enigmatic owner, Bishop Crane, needs an airtight alibi to avoid a murder charge.
He demands Gemma move into his heavily surveilled penthouse and play the role of his devoted girlfriend. In exchange, he'll give her the evidence she desperately needs. As Gemma steps into Bishop's meticulously controlled world, the boundaries of their fake relationship begin to blur. Bishop is obsessive, possessive, and harbors dark family secrets tied directly to the underground network that took Gemma's sister.
But the most terrifying discovery isn't the criminal conspiracy-it's the realization that Bishop has been secretly watching Gemma for eleven months, building a gilded cage designed specifically for her. Torn between her desperate need for the truth and the magnetic, dangerous pull of the man who controls her every move, Gemma must decide where the line is drawn between protection and possession.