Cleveland Winston Silvestter is a paranoid, misanthropic billionaire businessman who, after much deep study of the occult, "discovered" that Satan is the true God and controller of the world and that he, Silvestter, is his chosen disciple. Silvestter believes the complete destruction of the human race is necessary to make a new beginning - a new dawn - for Lucifer, with CWS as the new Adam!
His plan to bring it about: assassinate various world leaders and blame enemy nations. When the book begins, several leaders are already dead and only two assassination plots remain: the U.S. President and the Russian Premier. Silvestter plans to retreat to his 850,000-acre sheep ranch in northeast Australia and sit tight as the nations of the world annihilate each other with atomic weapons.
Richard Camellion, the Death Merchant, argues with the CIA about the best way to go after Silvestter. The DM wants to infiltrate his Manhattan skyscraper, but the decision is ultimately made - early in the book, page 44 - to waste him in Australia. So we know that the ultimate battle will come with Camellion travelling Down Under. Camellion first goes to Rome, to meet up with agents from Russia, Britain, France, and Australia, who will assist him in storming Silvestter's massive compound.
Camellion and the other assassins fly from Rome to Bombay and then are transported by yacht to Brisbane, which leaves plenty of time for conversation. And considering Silvestter's religious beliefs are key to the book, Rosenberger has the Death Merchant engage in not one, not two, but three separate arguments about religion. One of the discussions (which becomes a lecture when Camellion is talking) goes on for seven pages!
Whether it's Satanism or Christianity, each form of belief is based on the acceptance of sheer myth as concluded fact. Each is a narrow form of belief, and both are childish. ...Camellion does not elaborate on "the real creator of the universe". During the debate, the Russian agent discourses on the "sociopolitical domination" of organized religion and points out various inconsistencies in the four "inspired" gospels.
The world would have been spared a lot of pain and suffering if Christianity had evolved into a religion of tolerance as, say, Taoism or Buddhism. Instead the religion of the Bible is as intolerant and militaristic as any Hitler ... a religion that has to go out and conquer the world - and God help those who disagree with it, if you'll pardon the pun! ... The great tragedy is that none of it, not a damned bit of it, has anything to do with the real creator of this universe! ...
I deal only in facts! And I have refused to let myself be influenced by a religion that is more interested in money than men! Behind the Biblical idea of 'Jehovah' stands a political pattern of tyranny, of rule by violence, of mental and moral slavery.
During the voyage to Brisbane, they are met by a large enemy ship sporting an antiaircraft gun on its deck (a German 5.5-cm Gerat 58-AA). After a lengthy shootout - in which Rosenberger tells us what kind of gun each man is using - and some fancy maneuvering by the yacht's captain, Camellion actually leaps aboard the enemy vessel. In no time at all, he has killed everyone on board. Then, after pouring shark repellent over his body, he leaps into the sea and swims back to the waiting yacht!
When the men are back again on dry land, they are flown to within sixty miles of New Eden, and they set off in armoured jeeps. They are met with resistance once they cross over into Silvestter's land, but they get through and storm the main compound. There is a fierce shootout in a gym/pool area: "Pavel [the Russian agent] gave the last rites ... sprinkling them with holy lead from his blessed submachine gun ... From then on, the devil dunces would have to do their calisthenics in Hell ..."
[In the building's hospital] Two patients in bed were too ill even to hold weapons, but that didn't prevent Pavel from giving them shots not called for on their charts - a prescription of 9-mm slugs guaranteed to cure any aliment! No one ever complained about the dosage ...Rosenberger also delivers his usual hilarious (and often racist) descriptions of the goons and boobs gunning for the DM. This time, they are Italian: "spaghetti elbow bender ... garlic gobblers ... wop cops ... goofy guinea". Also, Silvestter's group of believers are described alliteratively as "Satan saps", "demonologist dummies", and "Lucifer lunatics". My favourite line, which came completely out of the blue: "The old bastard looked about as intelligent as a high-school football coach."
After driving into the underground compound and wasting everyone on the first floor, Camellion and his men quickly race through the other floors, making their way to the sixth and final level and the Hall of Conjuration. The DM and four men blast in, outnumbered 2:1 and quickly out of ammo. What follows is 12 pages of intricately described hand-to-hand combat! One of Silvestter's men catches a knife in the neck, his blood "spurting as thick as a pencil".
The Death Merchant emerges victorious. The CIA wanted Silvestter taken alive, but that was not possible. The epilogue has Camellion already contemplating his next mission: "I've got to go waste some sandcrabs!", i.e., Arabs in North Africa.