Ghost Signal

Acheron Colony was supposed to be humanity's greatest windfall. Using long-range sensors, the planet tested out as a super-earth—but the reality is frightening. Instead of finding a green world bursting with life, the colonists find a dead rock covered in ash. Something has dismantled every organic molecule on Acheron—and no one knows how or why.

When a mysterious signal that defies explanation begins to pulse from an alien ruin, the colonists panic. Something ancient was here long before them, and the signal, like a heartbeat, won't let them forget it.

Alien-built guardians arise, marching on the unsuspecting humans. Fearful they will be erased just like the last civilization, the colonists call to Earth for help. Special forces operative Dane Tanner of XCU responds to their pleas. Dispatched to Acheron with time running out, Tanner and the colonists must decode the Ghost Signal to either shut down the murderous guardians or harness their power.