<p>It is the middle of the 21st century</p><p>After the cataclysmic upheavals of Step Day and the Yellowstone eruption, humanity is spreading further into the Long Earth. Society, on a battered Datum Earth and beyond, continues to evolve.</p><p>And new challenges emerge.</p><p>Now an elderly and cantankerous AI, Lobsang is living with Agnes in an exotic, far-distant world. He's determined to lead a normal life in New Springfield--they even adopt a child. But there are rumors, strange sightings in the sky.</p><p>On this world, something isn't right . . .</p><p>Millions of steps away--learning about a hidden family history and the father he never knew--Joshua receives an urgent summons from New Springfield.</p><p>Lobsang has come to understand that what has blighted his Earth is a threat to all the worlds of the Long Earth. To counter this threat will require the combined efforts of humankind, machine, and the superintelligent Next.</p>And some must make the ultimate sacrifice . . .