Shadow in the Warp
The horror of a Tyranid assault on a prey world begins long before the first bio-construct sets foot on the surface. The unfortunate planet is first engulfed in a psychic signal that renders it utterly silent, all warp travel and communication made impossible. This mysterious and dread phenomenon has been named the Shadow in the Warp, and it is a harbinger of doom. It leaves the people of Imperial worlds unable to escape their fate, or to call for reinforcements that might be their salvation.