This is live Cluedo with lesbians. That, incidentally, is the recommendation. (And despite being American, I say Cluedo because Hall is basing it on the British version of the game and yes I looked up the differences.)
It’s not as fluffy as Hall’s usual romances because it’s not, at heart, a romance even if it is a story about love. 
Hall does something very interesting here in

the way he walks the line between mystery is interesting and murder is banal. It works; he doesn’t entirely undermine the idea of the genre even as he consistently wobbles its premises. It’s a book that can only have been written in response to true crime and Serial and Hall is very deft at what he does. The downside, of course, in cheerfully undermining the genre that you are writing, is that the reading experience itself takes on a certain amount of ironic detachment, which prevents immersion

.
I still can’t believe Hall got away with this book and also it’s precisely the kind of thing he could pull off.