Short answers, pulled from the story.
Robert Catesby led the Gunpowder Plot. Described by contemporaries as about six feet tall, athletic, and a good swordsman, he recruited the other conspirators and devised the plan to blow up the House of Lords during the State Opening of Parliament on the 5th of November 1605.
The conspirators, a group of English Catholics, hoped to end the persecution of their faith. Catesby is suspected by historians to have turned to violence after hopes of greater religious tolerance under James faded. James had reimposed fines for recusancy and in March 1604 ordered all Jesuits and Catholic priests to leave England.
On the 26th of October 1605, an anonymous letter was delivered to William Parker, 4th Baron Monteagle, warning him to avoid Parliament. Monteagle immediately gave the letter to the Earl of Salisbury. A search on the night of the 4th of November found Guy Fawkes guarding 36 barrels of gunpowder in the undercroft beneath the House of Lords.
Fawkes was taken to the Tower of London, where King James authorised torture. He was almost certainly subjected to the rack and confessed on the 7th of November. He was convicted of high treason at trial on the 27th of January 1606 and executed in the Old Palace Yard at Westminster the following day.
Henry Garnet, the principal Jesuit of England, learned of the plot through a confession relayed by the priest Oswald Tesimond. Canon law's seal of the confessional prevented him from informing the authorities. He was convicted of high treason and executed on the 3rd of May 1606, though his precise level of involvement remained disputed.
The Observance of the 5th of November Act 1605 was passed in January 1606, making annual commemorative services compulsory in England. The act remained in force until 1859. The tradition of bonfires, bell-ringing, and fireworks began soon after the plot's discovery and evolved into the Bonfire Night celebrations still observed across Britain on the 5th of November.