During a surveying mission to find water deposits within craters on the Moon, Aldion and his team discover a covert underground structure.  No-one knows who built it or why.

The discovery is the flash-point that triggers the latent hostility between the now-private security agencies of Earth – leading to an escalating series of conflicts. Threaded through these conflicts, Carth must try to get to the structure first to avoid an unthinkable loss.