Primal Fear is a 1993 American thriller novel by William Diehl about Aaron Stampler, an altar boy accused of murder, and Martin Vail, the attorney defending him. It was adapted into the 1996 film of the same name, starring Richard Gere and Edward Norton. The characters of Stampler and Vail appear in two additional novels by author Diehl, Show of Evil and Reign in Hell.

Plot

Martin Vail, a lawyer of "bad-boy" fame, is defending Aaron Stampler, who is seen standing with a bloody knife when the Archbishop of Chicago was murdered. Knowing he would lose, Vail used his unorthodox skills to take legal advantage.