In the mysterious and fog-laden streets of London in 1908, the tenacious journalist and women's rights advocate, Sonia Winter, uncovers the secretive operations of Assassination Bureau Limited. Determined to bring down this ruthless syndicate, she sets a hefty bounty of £20,000 for a hit on the bureau’s compelling chairman, Ivan Dragomiloff, all arranged through her influential patron, Lord Bostwick.
Surprisingly, the hit that Sonia requests does not infuriate Dragomiloff; instead, he views it as an intriguing opportunity to reclaim the bureau's lost moral compass. He enlightens her about his organization's past, which once aimed at targeting tyrants rather than making a profit, but recently shifted towards financial gain. Dragomiloff makes a bold move by agreeing to accept his own assassination, throwing down a challenge to Sonia and his own assassins: either they kill him, or he will eliminate them.
Thus begins Dragomiloff’s perilous adventure across Edwardian Europe with Sonia at his side, as they set out to systematically eradicate the bureau’s senior members. Their first destination is Paris, where he adopts the persona of Le Comte and visits a notorious brothel. Unexpectedly, Sonia appears, leading to a heart-pounding escape down a laundry chute as chaos ensues with a police raid and explosive booby traps.
After a narrow escape, Sonia finds herself apprehended while Dragomiloff narrowly avoids capture. Their next encounter arises aboard a train to Zürich, where a train waiter named Popescu attempts to kill Dragomiloff with a gun. However, Dragomiloff cleverly retaliates using fiery brandy from his cigar to fend him off, resulting in Popescu’s dramatic ejection from the train.
In Zürich, amid a mistaken terrorist scare, Dragomiloff seizes the moment to plant a real bomb, leading to a catastrophic incident that claims the life of a bank manager named Weiss. As they witness a grand military parade in Vienna, a plot unfolds where Dragomiloff subtly implies that if “the Assassination Bureau” had undertaken the task of protecting the Archduke, he would undoubtedly still be alive today.
Travelling to Venice, the plot thickens as Cesare Spado, a member of the Bureau, meets his demise at the hands of his wife, Eleanora, who teams up with her lover Angelo in a reckless attempt to murder Dragomiloff. Their sinister endeavors lead to a failed assassination on Sonia, but Dragomiloff's expertise allows him to evade these threats and retaliate against both Angelo and Baron Muntzof, ultimately saving Sonia from peril.
After losing her husband's protective affiliation, Eleanora attempts to bargain her knowledge of the Bureau's existence for a handsome payoff. Sadly for her, this desperate maneuver only results in a death sentence executed by the Bureau on the orders of General Pinck.
Unbeknownst to Dragomiloff and Sonia, their actions have inadvertently paved the way for Lord Bostwick, played by Telly Savalas, to set into motion a devious plot. Vice-chairman of the Bureau, Bostwick holds a deep-seated grudge against Dragomiloff for being chosen over him by the founding leader. With revenge on his mind, Bostwick crafts a scheme to capitalize on Europe's instability, buying shares in armament companies with plans for a cataclysmic war.
Bostwick and the Bureau's remaining cohorts devise a scheme to exploit the tensions in Europe by orchestrating a large-scale conflict. Their aim is to eliminate all European heads of state and secure their financial advantage. They infiltrate a crucial peace conference where fragile treaties are being negotiated to avert war following an accidental assassination of a Balkan prince.
As the situation becomes increasingly tenuous, Sonia and Dragomiloff uncover Bostwick's nefarious plan which involves commandeering a Zeppelin to unleash a devastating bomb on the castle where the peace summit is being held.
Without a moment to lose, Dragomiloff leaps into action, commandeering the airship to dismantle Bostwick's insidious plot. He manages to dispose of the bomb and confronts General Pinck in a gripping duel, which he triumphs in once more. As a result of his valiant efforts, he earns accolades from the very leaders he has saved. With his reputation restored, Dragomiloff finds himself poised to finally propose to Sonia, sealing their adventurous journey with a vow of love.
