A man is murdered in a phone booth on Waterloo station while Simon Templar is making a call. But before his death he has managed to slip a mysterious package of "Miracle Tea" into the bag of a young nurse who works at the naval base at Portland. Now the Saint wants to know why.
In the Australian outback the Saint tricks two greedy and quarrelsome brothers into repaying their old father money that they have long owed him when he tempts them with the offer of shares in a silver mine.
The Saint is in Munich for the Oktoberfest when a friend of his, American Army Sergeant Henry Johns, is killed whilst trying to stop an armed robbery at his base. Unbeknown to him, Mathilde Baum, whom he believed to be his girl-friend, was actually part of the gang, using her friendship with him to gain insider information. Furthermore, she is now getting cosy with another American soldier, Sergeant Pargo, who was a friend of Johns. He teams up with the Saint to go after the hi-jackers and avenge their dead buddy.
Simon helps an Italian family who owns a London restaurant when a conman leaves one of their members with child. The Saint takes a particular interest when he discovers the conman left the country with a million pounds.
In South America the Saint meets two swindlers, Alice Nestor and her father. They show him a golden statue of a frog, claiming it is one of many such icons of the sacred frogs of the Incas and request that the Saint backs their expedition to find others. The Saint pretends to co-operate but plants some fake gold of his own to turn the tables on the swindlers, only to discover that they are also gun-runners for local revolutionaries. He sets out to thwart them.
On the island of Haiti, noted for voodoo, the Saint meets the beautiful Sibao, a mystical young woman, and her fiance, Theron Netlord, a young Englishman who is entranced by voodoo and is marrying Sibao purely to learn its secrets and gain power for himself. The Saint accepts an invitation to dinner with Netlord and finds himself in danger.
Betty Tregarth is forced to go with a group of men led by Bernhard Raxel. Earlier Chief Inspector Teal had told the Saint that he suspects Raxel of planning the 'crime of the century', having killed an undercover officer planted by Teal for more details. Betty works at a research plant perfecting nerve gas and Raxel has kidnapped her brother as security for her cooperation. He wants to employ nerve gas in a robbery to steal the plates and paper from the Bank of England's printing house. Teal intercepts one of the safe-crackers Raxel intends to use in the raid and ...
Television host Ziggy Zaglan has a jovial public image but is really a very unpleasant man who owes his success to the clever writing skills of his adopted brother, Paul. Paul is visited by James McCleary, a man who claims that Ziggy was responsible for his sister's death by drowning, and the next morning Paul is found dead by hanging. The assumption is that he killed himself but the Saint is not convinced and sets out to find the murderer.