What was the secret society?

The Secret Agent: A Simple Tale is a novel by Joseph Conrad set in 1886. The protagonist, Mr. Adolf Verloc, is the titular secret agent who works in London for an undisclosed foreign power. Verloc and his employer at the embassy could be viewed as a secret society. They seek to manipulate the United Kingdom through acts of terror. Verloc's handler tasks him with bombing the Greenwich Observatory with the hope that it will spur the London government into cracking down on the local anarchists.
In addition to using the anarchists as scapegoats, Verloc also takes advantage of his mentally challenged brother-in-law. This decision blows up in Verloc's face as Stevie accidentally kills himself in the bombing. Verloc's grief-stricken wife kills him in revenge, is betrayed, and then finally takes her own life. The secret society failed in their plot and harms everyone involved.