The context: 1965 to 1990, Five discoveries at Shell -- Introduction to scenario-based planning -- Three competing paradigms in strategic management -- The principles of scenario-based planning: Strategising -- The business idea of an organisation -- The uncertain environment -- Scenario analysis -- Scenarios and the strategic conversation -- The practice of scenario-based planning: The practitioner's art -- Articulation of the business idea -- Competitive positioning -- Scenario development -- Option planning -- Institutionalising scenario-based planning: The management of change -- Planning process -- Guiding the strategic conversation -- Conclusion.