Ice

He was wandering through a labyrinth of frozen passageways. He knew he was below ground, or at least beneath a significant amount of ice.
Everything was white. He had wandered for a long time. He couldn't remember how he had ended up where he was, but he was appropriately dressed for the conditions and assumed he was meant to be there.
He turned on to yet another icy corridor and saw something different. There were compartments along the wall. In each one was a body, frozen solid.
He approached one that was empty. There was a sudden, sharp blow to the back of his head.