Several extremely rich men have died under suspicious circumstances, and Karl Zweig, a professor of philosophy, has reason to suspect they were murdered by his former student, Gustav Neumann, a brilliant young man who had once espoused the desire to become a master criminal. When he observes Neumann in the company of Sir Timothy Ferguson, a wealthy and sick old baronet, Zweig believes he may soon be Neumann's next victim. But as Zweig races to gather evidence against his old friend, he begins to be unsure whether any murders have been committed at all. Instead, Neumann may be involved in something even more disturbing and bizarre than anyone could ever imagine . . .   

First published in 1964, Necessary Doubt is a suspenseful and page-turning thriller that reflects Colin Wilson's lifelong interest in crime and murder and explores intriguing questions of existential philosophy. This edition is the first in more than thirty-five years and features a new introduction by Colin Stanley.