In London, in 1908, aspiring journalist and women's rights campaigner Sonia Winter uncovers an organisation that specialises in killing for money, the Assassination Bureau Limited.

To bring about its destruction, she commissions the assassination of the bureau's own chairman, Ivan Dragomiloff for £20,000 after being bankrolled by her employer, Lord Bostwick.

The guiding principle of his bureau, founded by his father, has always been that there was a moral reason why their victims should be killed; these have included despots and tyrants.

He meets Miss Winter at the Albert Memorial and with her in tow, Dragomiloff sets off on a tour of Edwardian Europe, challenging and systematically purging the bureau's senior members.

They escape down the laundry chute, but leave a booby trap that blows the room up when the door is eventually smashed in, killing Lucoville.

He pulls a gun, but Dragomiloff sprays him with fiery brandy, lit by the cigar, burning his face and he jumps off the train and dies.

In Zürich the bank manager Weiss pulls a gun on a suspicious-looking customer and throws his bag into the street, thinking it is a bomb.

Bostwick and the other surviving members of the Bureau plan to get rich quick by the "biggest killing" of them all, namely buying stocks in arms companies and then propelling Europe into a world war.

They attend a secret peace conference where the kings, emperors, and prime ministers of Europe are trying to avoid a possible war over the assassination of a Balkan prince who had accidentally been killed by a bomb intended for Dragomiloff.

Dragomiloff and Miss Winter uncover the plot, which is to drop a large aerial bomb from a hijacked Zeppelin airship directly onto the castle in Ruthenia where the peace conference is being held.

Dragomiloff steals aboard the airship and destroys the bomb, while disposing of Lord Bostwick and the remaining members of his board of directors.