We take a ride on the rails across the cosmos once again with Zen Starling, once a thief, now living in tedious luxury. Nova is gone - she's disappeared into the vast reaches of the Black Light Zone - and without her, Zen's life seems pretty meaningless. He's not even allowed to travel to the new worlds that he helped open up. So when he receives a cryptic message, he wastes no time. Nova is out there, and she needs his help. Threnody is now the head of her family, but the empire they used to rule is now split in two, and she rules only half of it. If that - she feels she's more of a figurehead, a puppet. Her journey to fulfil her potential will be both terrible and awe-inspiring. And Nova - Nova has become something bigger than before. Much bigger. And yet there's still room in her artificial heart for Zen - and a plan for one last heist. A heist that will solve the mysteries of the Railmaker, the godlike entity who created the rail system that spans the galaxy. Add in our favourite intelligent trains Damask Rose and Ghost Wolf, a host of malevolent AI gods who'll stop at nothing to prevent the resurrection of the Railmaker, and a civil war between the two halves of the empire, and you've got all the ingredients for a thrilling adventure featuring the characters we've come to love over the series. Like all good sci-fi dealing with artificial intelligence, it questions what it means to be human; it never lets the philosophy slow down the pace, though. Brilliant, vivid, thrilling, and moving, this is an excellent conclusion to the trilogy. Highly recommended.