1.
plot; synopsis; storyline
The outline or summary of a story, play, or film. Refers to the sequence of events that make up a narrative.
2.
scenario; script; planned course of events
A planned or expected sequence of events, often implying that something was orchestrated or prearranged.
Usage
Often used in the expression 筋書き通り (according to the script/plan). In sense 2, it carries an implication that events were prearranged or orchestrated rather than happening naturally.