The main plot line centers on Norman Cash, a middle-aged police detective sergeant at St. Louis, Missouri, and his younger partner John Harald.

The body was found near the home of an old lady of Central European origin named Fiala Groloch, who politely receives the police in her old-fashioned parlor, offering them tea.

After some time, Cash takes up the Groloch investigation again, and from a rather "loony" affair it becomes deadly serious and grim: evidence is discovered that at various times people who went into the old lady's house disappeared without a trace, including several armed gangsters; then Cash's partner John also disappears when attempting an unauthorized search of the house; when police raid the house in force, they find the old lady gone, and mysterious machinery hidden in the basement turns out to be bobby-trapped, exploding and causing more police casualties; then in another part of the town, the house of a doctor – also a refugee from Europe – burns and mysterious bodies are found in the wreckage – which seems somehow tied to the Groloch affair; and the CIA turns out to have a considerable interest in all these doings... Cash, now bitterly determined to settle accounts with the sinister Groloch, has one ace left up his sleeve: he knows of another Groloch who had been living for a century at Rochester, New York, assumes that the fugitive woman went there, and sets out in pursuit.

The State's virtually invincible weapon is the Tachyon Displacement Data Transfer System by which the Agency can send messages into the past, warn itself of coming threats and take action to eliminate them.

But the psychotic Colonel Neulist, consumed with jealousy of the Zumstegs and angry because Otho's daughter Marda rejected his advances, bursts into the chamber and starts wildly shooting – causing the Tachyon system to explode.

In possession of advanced medical knowledge which can extend human lifespan to two hundred years and more, they decide to take the slow road back to their own time.

In 1942, it is the nefarious Neulist who manipulates the Nazi occupiers to destroy Lidice, causing one of the most notorious atrocities of World War II to be perpetrated just in order that his hated rival be among the victims.

In Beijing, the genius psychologist and spy master Huang Hua had spent decades secretly improving the methods of brainwashing which had not worked out in the Korean War.

With the outbreak of the Vietnam War, the Chinese get their North Vietnamese allies to secretly deliver some American prisoners to Huang's installation in the Gobi Desert.

Huang decides to keep him and a few other Americans in China, while other brainwashed prisoners are sent back to Vietnam and eventually repatriated – to act as Chinese sleeper agents in the US.

He was destined to be sent to hard labor and die unknown in China – but Michael Cash connives at letting him join the repatriated prisoners, carrying back his knowledge of the Chinese brainwashing program.

Meanwhile, Michael Cash had been sent to Prague, to establish Chinese contacts with dissenting elements in the local Communist Party towards an eventual showdown between China and the USSR.

He succeeds in the mission – but has also fallen deeply in love with his Czech Communist contact person, a woman named Ilse, left her bearing his child, and dreams hopelessly of building a life with her.

... Detective Sergeant Norman Cash believes that "The Fall of Saigon marked the East's watershed victory in World War III.