The Labyrinth House Murders by Yukito Ayatsuji, the newly-translated third book in the Bizarre House Mystery series, is down to £1.99 on the UK Kindle store, today. (Book one - The Decagon House Murders - is really outstanding, but I saw through book two - The Mill House Murders - almost immediately.)
https://www.amazon.co.uk/Labyrinth-H.../dp/B0DCG8CSRC