Hard to swallow.
Important to progress.
Who are the puppet masters?
Have the puppet masters traveled to this island?
When? How often? Why?
The Puppet Masters- Robert A. Heinlein (1951)
American secret agents battle parasitic invaders from outer space
Heinlein repeatedly makes explicit the analogy between the mind-controlling parasites and the Communist Russians, echoing the prevailing Second Red Scare in the United States.
The book takes up the then common theme of sightings of Flying saucers, the plot assuming that that the "saucers" seen in the 1950s were part of a preliminary reconnaissance of Earth, carried out by the extraterrestrials in preparation for a full-fledged invasion sixty years later.
However, communications satellites have not been thought of, and television broadcasts are still limited to line-of-sight, as they were at the time of writing. This is of critical importance to the plot. The territory of the United States is divided into numerous transmission blocks, which receive television broadcasts from their neighbors and relay them onwards. When the invaders seize one of these blocks, they effectively control all communications within it and can isolate its inhabitants from the outside world, deny the central government any access to them, and consolidate control at their leisure.
The current President - on his second term, and therefore presumably elected in 2000 - had established directly upon being first elected a new intelligece agency, known as The Section. Its creation was never authorized by Congress and its existence is kept secret, being funded by sums diverted from innocuous sounding items in the Budget. It has a disguised underground headquarters in Washington D.C. and a network of similarly disguised branch offices around the US. Unlike the clearly demarked spheres of the FBI and CIA, the Section carries out extensive espionage in Soviet territory, but also conducts operations inside the United States. If ordered to, its agents are ready to shoot and kill American citizens on US soil. The Section's Director, who had been the President's campaign manager, is universally called "The Old Man". Only gradually does the reader learn that he is the protagonist's actual father.
In the summer of 2007, Earth is under clandestine attack. Slug-like creatures, arriving in flying saucers, are attaching themselves to people's backs, taking control of their victims' nervous systems, and manipulating those people as puppets. The Old Man, the head of a clandestine national security agency called the Section, goes to Des Moines, Iowa, with Sam and Mary, two of his best agents, to investigate a flying saucer report, but much more seriously the ominous disappearance of the six agents sent previously. They discover that the slugs are steadily taking over Des Moines, but they cannot convince the US President to declare an emergency.
Adopting biological warfare, the authorities culture Nine-day Fever and its cure in bulk sufficient to cover the country, and then infected slugs are allowed to escape into the heavily infested areas. Several days later thousands of medics are landed in those areas to give the cure to those people whose slugs have died. Sam and the Old Man join the effort in Jefferson City, Missouri, but the Old Man is possessed by the last healthy slug in the city and he knocks Sam out.
https://en.wikipedia.org/wiki/The_Puppet_Masters
A book about General Flynn & Donald Trump