Word Origin & History
plotO.E. plot "small piece of ground," of unknown origin. Sense of "ground plan," and thus "map, chart" is 1551; that of "plan, scheme" is 1587, probably by accidental similarity to complot, from O.Fr. complot "combined plan," of unknown origin, perhaps a back-formation from compeloter "to roll into a ball."
Meaning "set of events in a story" is from 1649. The verb is first attested 1589 in the sense of "to lay plans for" (usually with evil intent); 1590 in the lit. sense of "to make a map or diagram."