The gunpowder plot, led by Robert Catesby and Guy Fawkes, occurred in 1605. The plotters (through Thomas Percy) rented a house adjacent to Parliament, and eventually rented a coal cellar below the House of Lords, which was to serve as a place to set their 36 barrels of gunpowder off. The plot was discovered, by means that are far from clear, and the conspirators fled London. Guy Fawke was caught in London, and executed. Catesby, along with two others was slain when apprehended.
Scott's "The Fortunes of Nigel" was written for a timeframe immediately around the Gunpowder Plot, during the reign of James I. His introduction contains a reference to it:
"...The gunpowder fright is got out of all our heads, and we are going on hereabout as if the devil was contriving every man should blow up himself by wild riot, excess, and devastation of time and temperance...."