plot: [11] Two separate and unrelated words have come together to form modern English plot. The earlier was late Old English plot, a term of unknown origin which denoted ‘area of ground’ (as in a ‘plot of land’). This subsequently developed to ‘ground plan’ and ‘diagram’, which formed the basis of ‘set of events in a story’ (first recorded in the 17th century). The other ancestor was Old French complot ‘secret scheme’ (also of unknown origin), which was originally borrowed into English in the 16th century as complot, but soon lost its prefix com-, no doubt under the influence of the already existing noun plot.
