Help me find please

It starts off with a woman going to the club with her friend ands he sets her mate up with someone.
They all get to drink and she needs the restroom on her way to the restroom it has a long line so she tries somewhere else, she stumbles in on a room with a few people sitting there this strange man lets her use the restroom and invites her to sit with him. I think his name is jack!
Not long after he tells her to leave with her friends but doesn't give her a reason. So she does and then she find out that that club after she left a few men got shot.
I've been trying to find the book for weeks.