Public key encryption works by using a public encryption key and a private decryption key. Anyone can encrypt a message with the public key, but only the private key holder can decrypt these messages. This works thanks to some fancy math which effectively makes reverse-engineering the private key infeasible.
Storytelling seems to work in much the same way. Early on in a narrative, the audience is presented with the majority of relevant details which compose the core narrative. A keen mind can often discern these features. Yet, the core narrative remains obscured by the sheer number of configurations into which these details can be assembled. The story has been publicly encrypted. Only with the help of the author can the final, correct configuration be discovered.