Short answers, pulled from the story.
The Babington Plot was a plan to assassinate Queen Elizabeth I of England that took shape in 1586. The conspirators aimed to rescue Mary Queen of Scots from imprisonment and restore Catholic rule in England.
The chief conspirators were Anthony Babington and John Ballard. Babington was a young recusant recruited by Ballard, who was a Jesuit priest hoping to rescue the Scottish queen.
Sir Francis Walsingham used double agent Gilbert Gifford to intercept messages between Mary and her supporters through a beer barrel containing a watertight box. Thomas Phelippes decoded the ciphered letters sent via this method to provide evidence for execution under the Bond of Association.
Mary Queen of Scots was executed on the 8th of February 1587 after being tried at Fotheringhay Castle in October 1586. She was beheaded in front of 300 witnesses after signing her death warrant by Queen Elizabeth I.
Conspirators including Babington and Ballard were sentenced to death for treason and executed on the 20th of September 1586. They faced hanging drawn and quartered though public outcry led to changes in how the second group of seven men was treated during execution.