I’m currently reading A Book of Bones by John Connolly (part of the Charlie Parker series). One element that struck me as quite effective was the use of stories within the main story. My favourite section so far involved rival apprentice archaeologists in the 1920s under the supervision of a more seasoned archaeologist; with the latter narrating a horrifying incident on the Hexham Moors. The tone and style of this section is radically different to other parts of the novel, sounding more like an MR James short story. I really liked this little digression.
Of course, this literary device is as old as the hills, with Shakespeare’s “Conscience of the King” play within a play in Hamlet as a good example. Hamlet seconds the services of a travelling theatre company to stage a play that re-creates the circumstances of his father’s murder at the hands of his uncle Claudius. He intends to watch his uncle’s reactions closely, to see whether they corroborate his father’s ghost’s account of his own murder.
More recent examples include the astonishing Tales of the Black Freighter within Alan Moore’s graphic novel Watchmen (revered as the Citizen Kane of graphic novels by comic book enthusiasts). In this context, the Black Freighter story is a metaphor for the journey into madness taken by the antagonist.
Nocturnal Animals also has a similar device which I won’t expound on here, except to say that I defy any serious writer of fiction to come away from that film unmoved or unchanged.
In my own novels, I have occasionally employed this narrative tool. Most notably, my gothic mystery thriller The Birds Began to Sing concerns an aspiring author who finds herself enrolled in a mysterious competition at a sinister mansion, to write the ending for an unpublished manuscript penned by a famous, now deceased thriller novelist. This unfinished novel has a horrifying secret from the real world buried within it, which eventually comes to light as the story progresses. (You can check out The Birds Began to Sing here).
All things considered, when done well, I think the story-within-a-story approach can work wonders to add depth to a tale. One caveat though: it cannot merely co-exist with the main story. It has to overlap or provide commentary and insight in a relevant, meaningful way. Otherwise, it’s not a story within a story. Just two separate stories.