Flan O'Brien wrote The Third Policeman in 1939 - 1940. However, it was not published until 1967, after his death, as the publishers considered it too fantastic. And it is fantastic.
The novel opens with the claim: 'Not everyone knows how I killed old Phillip Mathers...' So at once we know we have a first person narrator. Now, whilst it may be unfair to characterise all first person narrators as liars, they are invariably unreliable. And in this case, fantastically so. Indeed, the reader (this one at any rate) does not realise just how unreliable until almost the very end. However, just in case you have not read this work and might wish to do so, I will refrain from giving the game away.
Well, the central character - one can hardly call him the hero - tells us how he came to murder old Mathers. And fantastically, it's all down to a book, an index of the works and commentaries on the incredible scientist and philosopher, de Selby. The crime was committed in partnership with his insubordinate servant, John Divney, whom he discovers he can no longer trust and thus the two become inseparable, taking to the same bed. After three years of this intolerable mistrust and suspicion, the partners in crime set out to collect their ill-gotten loot. However, something mysterious happens and the central character is cast upon a series of strange adventures, a quest that brings him into contact with two strangely bicycle-obsessed policemen. It is only when he meets the third policeman that he is enabled to once more meet up with his untrustworthy partner.
All though the book the central character makes reference to the strange ideas of de Selby and O'Brien helpfully provides detailed footnotes to highlight points of controversy and conflict, especially in respect to the views expressed in the commentaries.
Whilst doing all this, O'Brien manages to convey it all in the language of his native land, which merely serves to lend yet a further fantastical twist to an already outlandishly fantastical plot. The novel is a subtle, wry, ironic and intelligent play with the art of storytelling, the nature of reality and our capacity to know and understand it; it is catholic in every sense of the word.