Smith consulted his watch very deliberately. "You have one hour to find the Imnulate and hand it over to me. If you do not, I will tear this train and its passengers apart piece by piece!"

Tempest: a wild and untamed world perpetually wreathed in cloud and storms. The only means of long-distance travel across its surface are the great transcontinental monorails that traverse its lonely and dangerous wastelands. Returning home from a lucrative lecture, Professor Bernice Summerfield finds herself on the most celebrated of these mighty trains.

The Drell Imnulate: a fabulous and unique religious idol. Precious enough to kill for. So important to those rival factions who follow the way of its maker that they will dare anything to ensure its return.

Isolated in the wilderness and far from civilisation, death strikes the luxurious Polar Express, and a routine journey turns into a nightmare. But can Bernice save a train on the brink of disaster?