This event brought about the raid of Holbeche House, and Thomas Percy rented the room where it was planned. It began to unravel when William Parker, who was meant to be spared because he was Catholic, read aloud a letter given to him, warning him not to be present in the targeted place. Lord Monteagle discovered the primary actor, posing as a Mr. John Johnson, guarding a supply of explosives. For 10 points, what was this 
This event brought about the raid of Holbeche House, and Thomas Percy rented the room where it was planned. It began to unravel when William Parker, who was meant to be spared because he was Catholic, read aloud a letter given to him, warning him not to be present in the targeted place. Lord Monteagle discovered the primary actor, posing as a Mr. John Johnson, guarding a supply of explosives. For 10 points, what was this plot organized by Robert Caseby in which Guy Fawkes was meant to blow up the Houses of Parliament?
This event brought about the raid of Holbeche House, and Thomas Percy rented the room where it was planned.
{Gunpowder} Plot