The Adventure Path is available for purchase and download as a digital PDF exclusively through the Paizo Store . While the full adventure modules must be purchased, Paizo offers a free Tyrant’s Grasp Player’s Guide PDF to help players prepare for the campaign’s unique survival-horror themes. Official PDF Purchase Links
The campaign consists of six individual volumes. Each can be bought separately for approximately $19.99: Paizo Store Pathfinder First Edition - Adventure Paths - Tyrant's Grasp pathfinder tyrant's grasp pdf download