Early in 1978, a young Melbourne cop is seconded to Special Branch to be part of a covert joint task force. He is to infiltrate a religious sect blamed for the Sydney Hilton Hotel bombing. It is there Jack Davidson receives his personal call sign--a recognition of his birthdate, Scorpion. This story follows Jack's adventure from uniform work to plainclothes work and into the Criminal Investigation Branch. Eventually, disillusioned and aggravated by the level of police corruption, he gives up police work to become a soldier. He enjoys army life, until they decide his police background is too valuable to leave him in the infantry. He is sent to Army Intelligence. In time, he leaves the army and gets on with civilian life.

Until one day he is contacted by an ASIO agent he knows from his police days. Following the September 11 attacks in the United States, the Australian government secretly decides to create a new covert security service dedicated to anti-terrorism matters. and they want to recruit Jack. He accepts the position and soon finds himself immersed in the dark and murky world of spying. A world where life is cheap, and truth means nothing.