This is a short tale by Anatole France from his 1892 collection L’Etui de nacre (Mother of Pearl). The full French text can be found here and an English translation here. The extract I’d have opted for feels both too much a spoiler and too insignificant when pulled from context – since the artistry of the tale is very much in its continued denial, a sort of variant on the Holmesian curious incident of the dog in the nighttime.
And in passing – I don’t have access to it right now but there’s an Italian translation with a preface by Leonardo Sciascia that is surely worth reading.
Extracts 