I hold John Sladek’s second and final detective novel Invisible Green (1977) in very high regard indeed, but have not read his first, the slightly less successful Black Aura (1974), for well over a decade. It’s pretty incredible that something which gave so much air to three baffling impossibilities was written as late as 1974 at all, and so revisiting it and finding a book which doesn’t quite fulfil the expectations of any idiom — it’s too puzzle-focussed for the gritty style that was popular at the time, but too nebulously handled to satisfy true puzzle heads — isn’t really a surprise. There’s still some enjoyable stuff in here, but this is very much the apprentice work for the masterpiece Sladek would produce three years later.