The destinies of Nathan and Rachel Summers are inextricably linked. But when Cable helped defeat Apocalypse, he apparently wiped out his own future - including Rachel's emergence as the Mother Askani! Now only Phoenix remains - but she's stranded at the end of time with the man called Guant, the greatest mass murderer in recorded history! To save his sister, Cable must reach the unreachable - a place of unimaginable desolation called the House on the Borderline!