"A Touch of Brimstone" is the twenty-first episode of the fourth series of the 1960s British spy television series The Avengers, starring Patrick Macnee as John Steed and Diana Rigg as Emma Peel. It was filmed c. December 1965, and was first broadcast on British television on 15 February 1966. The episode was directed by James Hill and written by Brian Clemens. The plot involves Steed and Peel infiltrating the Hellfire Club (which replicates the historic Hellfire Club) whilst investigating harmful pranks on high profile political and business figures.