All the Colours of Darkness by Peter Robinson
In Number 18 of the Inspector Banks series, Peter Robinson begins with a murder-suicide between two class-crossing gay men, and slowly begins to weave in suggestions that this case is tied in with the past of one of the men, Lawrence Silbert, who used to work for MI6.
Narrated by Simon Prebble, this story projects a dark atmosphere on the beauty of the Yorkshire Dales, and brings Inspector Banks ever closer to dangerous information he can reveal neither to his current lady friend, nor his trusted fellow officer, Detective Inspector Annie Cabbott.
In a break from the usual heavy plot line, Annie's colleague DI Winsome Jackman shares a few good scenes with Annie and gets the best of some petty criminals. Of course, she gets chewed out later by Chief Superintendent Gervase for risking her neck.
Meanwhile, when Chief Superintendent Gervase seems too willing to bow to pressure from the Chief Constable to close the case, Banks is suspicious he suspects that her boss is in thrall to political higher-ups. Naturally Gervase doesn't want this dangerous idea bandied about.
Constitutionally unable to accept gag orders or simple solutions, Banks continues to pursue the truth, even when doing so comes at great professional and personal cost. He also continues to resort to alcohol to help him cope with the dangerous and unshareable information that comes into his hands.
Silbert and Hardcastle are dead, but Banks pursues his "Othello theory," pressing a suspect for more information about exactly how the deaths happened. Then just as things seem to be looking up, more tragedy hits from a totally unexpected direction.
It's another fast moving thriller from master of suspense Peter Robsinson. And with a new twist: when this one is over, the reader gets the feeling it's not really over. Along with Inspector Alan Banks, we await further developments.