The Seventh Arch is a Pathfinder adventure for four 1st-level characters. This adventure begins the Gatewalkers Adventure Path, a three-part monthly campaign in which a team of paranormal investigators unravel the mystery behind a mass amnesic episode which left them with lost memories and strange powers. This adventure also includes a gazetteer of adventure sites on the alien world of Castrovel, the Green Planet; new rules options perfect for paranormalist adventurers; and strange new creatures to befriend or bedevil your players.