Two lifelong friends unearth something on a ridge in the swamps of Louisiana that should never have been found, setting off an explosive chain of events that unleash a horror not of this world.Jack Larson telephones his best friend Cyrus Parnell, a professor at LSU in Baton Rouge, and begs him to come down to St. Mary Parish, Louisiana to a hamlet named Shadowcross. Larson has found something, and Cy is the only person he trusts to share it with.Sheriff Garret Bredenbury, a Wyoming mountain-man, is investigating a series of grisly killings, and the trail of the killer is leading due southeast...to Louisiana.And if Jack and Cyrus can't disentangle their mistake, the human race may be annihilated from the Earth.And never mind the psychopath who's trying to kill them, too.