Hellhounds of the Cosmos by SIMAK, Clifford D.

From Astounding Stories of 1932. Earth is being attacked by horrible black monsters that appear from nowhere and destroy and kill everything and everyone in their paths. Nothing affects them, nothing stops them; they are impervious to all weapons. Earth is doomed. But there is one hope and it rests on the shoulders of 98 brave men. Can they do it? can they find a way of retaliating? Listen and find out.