The Puppet Masters

The Puppet Masters is a 1951 science fiction novel by Robert A. Heinlein in which American secret agents battle parasitic invaders from outer space. The novel was originally serialised in Galaxy Science Fiction (September, October, November 1951).
The book evokes a sense of paranoia later captured in the 1956 film Invasion of the Body Snatchers, which had a similar premise. Heinlein's novel also repeatedly makes explicit the analogy between the mind-controlling parasites and the Communist Russians, echoing the then prevailing Second Red Scare in the United States.