Orbiting a quiet backwater planet, the massed forces of the universe's deadliest species gather, drawn to a mysterious message that echoes out to the stars. And amongst them, the Doctor. Rescuing Clara from a family Christmas dinner, the Time Lord and his best friend must learn what this enigmatic signal means for his own fate and that of the universe.

Death is only the beginning for the young victim of a drive-by shooting. Devastated at the loss of his younger brother Jermaine, scientific older sibling Ricky uses the situation as an opportunity to test an experimental serum designed to breathe new life into dead cells. Though Ricky's reanimation serum does indeed help to get his previously deceased younger brother back on his feet, Jermaine's insatiable hunger for human flesh soon spreads like wildfire throughout the neighborhood, leaving his older brother to find a way to halt the epidemic before the army of flesh-eaters become too powerful to be contained.