From publisher blurb:
HORRORS OF THE MIND UNLEASHED!
Within every creature lies the potential for destruction, for acts of cruelty and violation which sane minds can barely comprehend. Just as psionic power amplifies the abilities of the mind to change the world, it also magnifies the many horrors which linger in the dark recesses of thought few dare to traverse. Within this 40-page Pathfinder Roleplaying Game accessory are enclosed many dark and powerful secrets invoked by the most depraved of psionicists and those driven by fate to combat them. Those wishing to risk their sanity may delve within to unlock facets of psionic power previously untapped. Within you'll find:
Four new psionic archetypes for the Dread, Psion, Tactician, and Vitalist classes
Expanded options for the Zealot and Wilder classes
35 new psionic powers for all classes
14 feats for inflicting untold horrors on your enemies
Expanded options for psychic dueling and sanity rules
Three new corruptions for those who wish to sunder themselves for greater power.