The Secret Agent is a story of missed chances, misunderstandings and the pressures that can lead ordinary people to do extreme and savage things.

Set in 1886, it follows the bungling exploits of Adolf Verloc, the down-at-heel owner of a shop selling bric-a-brac, soft pornography and radical political tracts somewhere in the warren of backstreets in London's Soho. Living with and providing for his mother-in-law, wife and her mentally handicapped brother Stevie, Verloc seems the picture of shabby respectability but for two things: he is a member of an anarchist cell and a secret agent for an unspecified but distinctly Slavic foreign power.

When an administrative shake-up at the foreign power’s embassy puts a new man in charge, Verloc is suddenly called upon to prove his usefulness. After years of flying beneath the radar and leading a quiet life, he must shake the English establishment by detonating a bomb at Greenwich Observatory or else risk being dismissed from his position and losing the honorarium which has secretly subsidised his family’s existence.

Initially resistant to the idea, Verloc continues with his double life, hosting an anarchists’ meeting and running his shop, albeit with unease. Eventually, though, fate seems to place the materials for the attack into Verloc’s hands in the shape of his brother-in-law, Stevie, who becomes stoked up with strong emotions he barely understands after overhearing the anarchists’ bloody rhetoric.

News of an explosion under a tree in Greenwich Park and the remains of a man found at the scene spark a police investigation. Inquiries soon lead to the anarchist cell and - following visits from both Chief Inspector Heat and the Assistant Commissioner - Verloc’s wife, Winnie, realises that the dead man is her beloved brother and that her husband must be to blame.

When Verloc returns home, dismayed that his plans have backfired (Stevie was supposed to place the bomb at the Observatory and make his getaway, not trip and blow himself skywards), Winnie greets him coldly. There follows one of the great scenes in literature, in which husband and wife fence verbally, each unaware of the other’s knowledge, unwittingly cutting off all possible routes to understanding and reconciliation. At last, maddened by grief and frustration, Winnie seizes a carving knife and stabs Verloc to death.

Fleeing the house, Winnie bumps into Comrade Ossipon, a member of the anarchist cell who has always been attracted to her. Misunderstanding her garbled confession of events, he jumps at the chance to help her run away to France. At the last moment, however, with a clearer understanding of what he is getting himself into, he loses his nerve and abandons her to take the ferry ride alone, having stolen all her money.

Sometime later, news of a lady passenger throwing herself overboard from a cross-channel ferry is reported in the daily paper.