Last week frustration with democratic rule burst forth in a stab at the heart of government. For 18 hours Spain's parliament and Cabinet were held hostage in the chamber of the Cortes' Congress of Deputies by 200 armed men. The leader of the coup attempt, Colonel Antonio Tejero Molina, was no isolated madman. Within days of the bloodless collapse of the putsch, evidence emerged that Tejero had plotted with other officers, including three generals. Only the courage of King Juan Carlos and his commitment to democracy prevented Spain from plunging back into an authoritarian past that had ended with the death of Franco.