Cannon investigates the death of a double-agent, who was slain to make it appear a foreign government is unstable and thereby set in motion a plot to "liberate" the country.
Cannon meets an old acquaintance who is touring Europe as a concert pianist. Her special piano, which accompanies her on the tour, triggers a murder and Cannon suspects the pianist's menacing manager is implicated.
When the German police refuse to take Helen Davis' evidence of a gang of blackmailing biological terrorists seriously, she decides to investigate a story on her own and tracks them to their headquarters in Hamburg, Germany.
Cannon and Davis each receive a counterfeit ten dollar bill in an envelope. They discover that three million dollars were printed by the Germans during World War II but never recovered and are now stored near the Parisian flea market. The French police, however, do not believe their story.
Cannon interviews a fellow reporter in jail behind the Iron Curtain. The reporter was convicted of espionage, but the scribe tells Cannon he pleaded guilty only to protect an innocent girl.
Cannon boards a plane to interview two men convicted of black marketing. When the plane's two pilots are murdered the reporter wishes he'd listened to Helen's premonition of danger.
Cannon covers the murder investigation of a prime minister's secretary, who was killed trying to prevent spies from stealing state secrets. His investigation shows that the opposition party is trying to destabilize the government and alienate Western powers.
Cannon learns that a former newspaper reporter's life is in danger when the ex-newshound discovers racketeers have been stealing relief supplies earmarked for East Berlin.
When Cannon investigates corrupt business practices at a number of German steel mills, the ex-Nazi who owns them invites the reporter to his castle on the Rhine for a showdown.
While in a casino on the French Riviera, Cannon receives a tip to put 10,000 francs on "red five." The tip pays off, and Cannon gets a pocketful of money and the unwanted attention of a doctor and beautiful woman.
Cannon is summoned to the bedside of a dying man by two former circus performers. When he returns later in the day, he finds a different person occupying the bedroom.
Cannon is determined to prove to dwellers in a remote village that the ghost that supposedly haunts their valley is nothing but superstitious nonsense.
When a German Colonel supposedly hung for war crimes five years earlier is spotted, Cannon's efforts to report on the story are thwarted by the authorities.
Cannon is entrusted with a secret formula. In order to keep it from falling into enemy hands, Cannon memorizes it and joins a night club act to escape his pursuers.
