Perhaps, G. K. Chesterton's most famous novel, The Man Who Was Thursday has been tagged as a "metaphysical thriller." I suppose that's a good a description as any. But it's also a classic mystery and a classic fantasy and a classic spy novel and a classic whatever you wish to call it.
First published in 1908, the book follows Gabriel Syme, who is recruited by an anti-anarchist squad from Scotland Yard. Syme meets anarchist poet Lucien Gregory, who takes him to a local meeting of anarchists, whose leadership consists of seven men, each going by a day of the week. The local group is about to elect a person top fill the role of Thursday and somehow the choice falls on Syme. It turns out that at least five of the seven are in reality police informants out to expose each other and the group.
A surrealistic work, heavy on Christian allegory (Chesterton was a noted Christian apologist), but also embued with a great sense of pessimism; the novel has left many readers scratching their heads for well over a century. Novelist and critic Kingsley Amis did not scratch his head; pointing to the book's many twists and turns, he called it "the most thrilling book I have ever read."
Orson Wells wrote and starred in the Mercury Theater on the Air adaptation. In abridging the book for the radio, Wells dropped most of the metaphysical references that appeared in Chapter 14 of the novel, to make the story more palatable for his audience. The episode appeared toe month before the infamous War of the Worlds broadcast.
A brilliant and influential novel and an equally brilliant adaptation.
Enjoy.
https://www.youtube.com/watch?v=IH-32M_WoaY&t=5s