A cult, locked room murders, and a dual narrative with a crazy twist. An absolute treat of a mystery that both de and reconstructs the genre over the course of (almost) 300 pages. I really loved everything this work set out to do.
My only criticism is that there are three deduction chapters back to back to back at the very end, which gives a lot of whiplash. There are a couple stories layered on top of one another here, (or one story refracted a couple times) so the ending doesn't hit as quickly as it should since it will take most mortals time to parse what really happened when and where.