Even the best of men are punished for their good intentions. Leon Weber is in the final month of his prison sentence; he's about to go home to his son. But during a violent storm, his release comes sooner than expected, and the world he re-enters is overrun by an alien menace that hitchhiked through space on the tail of a comet. His journey to find his son will be fraught with danger and death, but the future of the world rides on his survival.