Among those principals was Thomas Percy, who rented the room at the center of the plan.
The implication of Oswald Tesimond in this affair gave the government impetus to search Jesuit households.  Thomas Bates, a servant of one of its leaders, was one of the few who managed to flee from the raid of Holbeche House, in which most of the principals were killed or arrested.  Among those principals was Thomas Percy, who rented the room at the center of the plan. A tip sent to Lord Monteagle led to a search of that basement of the House of Lords, where John Johnson was found with matches. FTP, name this 1605 attempt, led by Robert Cateseby and Guy Fawkes in 1605, to blow up the houses of Parliament and James I.
The implication of Oswald Tesimond in this affair gave the government impetus to search Jesuit households.  
Gunpowder Plot [accept Guy Fawkes Plot before his name is read; accept equivalent words for "plot"]