The plot, then, is the first principle, and, as it were, the soul of a tragedy; Character holds the second place. A similar fact is seen in painting. The most beautiful colors, laid on confusedly, will not give as much pleasure as the chalk outline of a portrait. Thus Tragedy is the imitation of an action, and of the agents mainly with a view to the action.
As with narrative, when I hear artists bemoan plot, I see confusion. Just as you cannot create a theatrical work devoid of narrative, you can not create one without plot.
Something happens onstage. Another thing happens. There is a series of events. Recounting/performing these events for an audience, is narrative. The order the events are recounted in, the arrangement and order of how the events and actions are performed is the plot.
I know it is often confused with Aristotilian-based theatre traditions. Plot is often conflated with the classical unities, mixed and rehashed as the well-made play a la Eugène Scribe, William Archer, and George Pierce Baker. Plot is often confused with realism or naturalism. None of these are accurate. Plot is a simple thing.
Aristotle in his Poetics tries to define perfection in poetry, perfection in tragedy. He makes subjective aesthetic choices about how plots should be constructed. How the pieces should be arranged, from what sources, etc. As to what plot is:
You can’t remove plot from performance, just as you can’t remove narrative. Narrative is the recounting of events-the pieces; Plot is how those pieces are arranged. Plot is the thread that ties the various pieces together to become a play. There are numerous combinations that can be crafted from infinite sources, depending on your aesthetic and cultural preferences; however, no works are free from plot or narrative. They are merely particles of performance.