First words, sentences and chapters.
In crafting a narrative there is an extensive amount of emphasis that is placed on the opening of the piece. Perfecting the hook of a narrative is one of the most important components of a piece but when the hook is set what comes next?
Whether it's the theme, conflict or the gestalt of the piece that piques the interest of an audience the piece doesn't end after the hook. The creator must continue to evolve their piece but also match the design of the hook. In many instances a vast amount of effort will go into refining the first chapter or hook so that an audience will be engrossed. Unfortunately the same effort is neglected for the proceeding chapters.
To sustain the curiosity of the audience it is necessary to orchestrate the premise in such a way as to nudge the reader to follow a character through a series of events. This is no different than taking the first hook and replicating it across pages where every page leads to the next.
The standard methods of creating narrative flow ensure cohesion between components however, the most notable methods to maintain interest in the piece is to never duplicate a situation or event. Every chapter should open with a new situation and not re-visit the events that brought the character to that point.
A supporting method to continue the cohesive flow of the narrative is to end each chapter with the hook, a 'cliffhanger.' If an audience is continually asking 'what is next' then it is possible to sustain their curiosity.
Every narrative is it's own mystery carefully crafted to sustain the curiosity of the reader. Like a guide casting breadcrumbs to lead their party to an unknown destination, the creator keeps the plot hidden to give them a chance to speculate. When the final pinnacle is reached it will ever the more breath-taking.