Gordon's data sheets were very, very good, but they can't really describe the screech that suddenly rings out as the first headcrab leaps out of the muck- or the vile, gorbling wail that the two half-gutted, clawed, faceless corpses make as they stagger forward under the control of the alien parasites completely encompassing their heads.

Dr. Kleiner gulps, but raises his shotgun to take aim.