Nothing But the Night (Basic Instincts #2) by Thom Collins

Be careful what you look for in the night.

Three months after the death of his brother, Marc Glass faces a whole new dilemma. A tabloid journalist has made a connection between Theo and a prominent politician. Theo’s death might not be all it seems. Marc knew all about his brother’s secret sex work, but it’s a scandal that would destroy his family, who have already suffered enough.
Private Detective Jason Durham might be the answer. Marc enlists Jason’s agency to look into Theo’s unsolved murder. The police investigation is dead, but if they can solve the case on their own, they could head off the potentially damaging story. Marc isn’t sure who he can trust with the details of Theo’s life, but Jason seems like the man.
As secrets are uncovered, Marc and Jason must fight their attraction to each other, but when their prime witness is murdered, they are suddenly caught in a web of mystery and increasing danger.

As the nights grow darker, will either of them make it until morning?