Psichopath by Randall Garret, Science Fiction, Fantasy (Paperback) (ISBN-13: 9781463800895)

One way to hide an ex-officio agency of the United States Government was to label it truthfully -- The Society For Mystical And Metaphysical Research. In spite of the fact that the label was literally true, it sounded so crackpot that no one but a crackpot would bother to look into it. As a consequence, better than ninety per cent of the membership of the Society was composed of just such people. Only a few members of the "core" knew the organization's true function and purpose.

A classic Randall Garrett tale . . .