Cmdr. Joe Hendrickson and new recruit Ace Jefferson set out across the surface of Sirius 6B, where they hope to settle a violent labor dispute at a remote mining outpost. After going too far to turn back, they find the desert riddled with deadly Autonomous Mobile Swords, or Screamers. Created to protect the mines, these burrowing weapons have learned to replicate themselves. To make matters worse, recent generations of Screamers can assume humanoid form.