Henry Garnet was born at Heanor in Derbyshire in 1555.  He travelled to Rome to join the Society of Jesus in 1575, and later became the superior of the English Jesuit mission.  He came to know of the Gunpowder Plot through the sacrament of confession, and was therefore bound not to reveal it, though he made efforts, in secret, to prevent it.

Following the discovery of the Gunpowder Plot in November 1605, the English government made extensive plans to track down the Jesuits, led by Garnet, whom they held to be the masterminds behind the plot.  Although all the plotters categorically denied any involvement by Garnet and his Jesuit colleagues, Robert Cecil was still trying to pin the blame on the Jesuits as justification for the Government’s severe anti-Catholic legislation.

On 27 January 1606, Garnet was eventually captured at Hindlip, home of the recusant Thomas Habington, along with the Jesuits Edward Oldcorne and Nicholas Owen.  The information on Garnet's whereabouts was supplied by Humphrey Littleton, who had been with the plotters on 8 November, and was now trying to buy himself a pardon.  This attempt was ultimately to no avail, as Littleton was eventually executed for complicity in the Plot.

Father Henry Garnet was executed on the 3rd of May 1606.