The science fiction classic,A Canticle for Leibowitz, is available in the public domain as an adapted audio serial from Old Time Radio via the Internet Archive.
Inspired by the author’s participation in the Allied bombing of the monastery at Monte Cassino during World War II, the novel is considered a masterpiece by literary critics. It has been compared favorably with the works of Evelyn Waugh, Graham Greene, and Walker Percy, and its themes of religion, recurrence, and church versus state have generated a significant body of scholarly research.
You can play it here.