On the twenty-fifth anniversary of the attacks that reshaped the modern world, Britain's chief domestic intelligence officer has offered a sobering reminder: the architecture of vigilance, however vast, is never complete. Speaking from institutional knowledge rather than abstraction, the MI5 director warned that a catastrophic attack of September 11th proportions may already be taking shape in the spaces between the searchlights — in regions and networks that the global security apparatus has, by necessity or oversight, chosen not to prioritize. It is a warning that speaks less to a specific t