This adventure was a con special released at a variety of conventions in 2009.
From the front cover:
A 4E adventure for 8th level characters.
A fiendish grell and its grimlock minions have plumbed the secrets of an ancient tomb, rumored to be a reliquary of the blind, exiled god Shargathor. They require only the blood of the innocent and a moonless night to gain possession of a terrible artifact and unleash the power of eldritch gods on an unsuspecting world. Now a moonless night draws near, and the heroes learn that a young girl has disappeared from the nearby town of Irondawn. Can they save her before she is sacrificed to the Old Ones in the dreaded Tomb of the Blind God?