Negotiation by Delta James

From bestselling author Delta James comes a mystery series with a hint of paranormal that’ll keep you guessing until the last page!

He’s a respected DSI with Scotland Yard; she’s a dishonored history professor running from a scandal.
Five years ago, Rachel Moriarty was caught up in gossip that resulted in losing her job as a tenured professor. She’s in London, focusing on building her exclusive tour business as well as her life.
Michael Holmes enjoys great success and a certain amount of celebrity acclaim due to his name, his reputation, and his uncanny ability to solve the unsolvable. He is intrigued by the woman who bears the last name of his greatest literary rival.
The veil between the worlds is weakening, something is trying to come through to bring its malevolence to a new generation. It’s found the key to unlocking the door, if only it can find a way to use Rachel’s innocence to re-enter this world.

Can Holmes and Moriarty work together to finally put an end to the evil that was Jack the Ripper?