St. Thomas Garnet is the son of Mr Richard Garnet, a distinguished fellow of Balliol College, Oxford. At 16, he went across the channel to the College of St. Omer. From there Thomas traveled somewhat adventurously to the English Jesuit College of Valladolid. He was ordained priest, and spent the next six years "wandering from place to place [in England] recovering souls that had wandered off and lost the faith of the one true Catholic Church."
After being arrested after the Gunpowder Plot, Thomas was tortured for information because of his close ties at home. He relinquished no information, and was transferred to Flanders, finally being set free after months of imprisonment in cold damp cells.
St. Thomas was soon after betrayed by an apostate priest, and rearrested. He was charged as being a priest by authority of Rome, and defying the Law of the England forbidding this. He did not admit to being a priest, for fear of judges having to convict him against their own consciences, and testifying against himself. In addition, he would not affirm the oath of Supremacy, which stipulated the King would have supremacy over all things temporal and spiritual in England.
St. Thomas was then accused by others, and condemned. The Earl of Essex tried to persuade him to avoid death by swearing an oath. He refused, admitted being a Jesuit and priest and telling of his wish to keep from the judges from having to act against their own consciences.
Though others tried to persuade him to accept the oath, Saint Thomas Garnet refused and was summarily hung. This was in AD 1608, and he was left for some time in order to be "sure" of his death.