Needle (novel)

Needle is a science fiction novel written by Hal Clement, originally published in 1950. It tells the story of a symbiotic pursuit between two alien lifeforms inhabiting human hosts.

The story centers around Robert Kinnaird, a teenager who discovers he is host to a Galorn, a microscopic, intelligent, and benevolent alien creature. Robert learns that the Galorn is hunting a Hunter, a parasitic and malevolent alien entity of the same species, that has also taken refuge inside a human being on Earth.

Throughout the novel, Robert must learn to communicate and cooperate with the Galorn to locate and identify the Hunter within the general human population. He learns about the Galorn's advanced medical technology and their shared history, which explains their long-standing conflict with the Hunters. The identification process involves painstaking investigation and careful observation, as the Hunter is adept at disguising its presence and manipulating its human host.

The novel explores themes of symbiosis, morality, and the importance of understanding alien cultures. Clement is known for his hard science fiction style, emphasizing scientific accuracy and logical consistency within his fictional worlds. Needle is considered a classic of the genre and is notable for its unique biological premise and focus on the relationship between the two alien symbionts.