Four months after the Pennine Fusiliers vanished from the Somme, they are still stranded on the alien world. Lieutenant Everson tries to discover the true intentions of their alien prisoner even as he must quell the unrest within his own ranks.

Beyond the trenches, Lance Corporal Atkins and his Black Hand Gang are on the trail of Jeffries, the diabolist responsible for their predicament, they must face the horrors that lie within the Croatoan Crater, a place tied to the history of the alien chatts and natives alike.

Above it all, Lieutenant Tulliver of the Royal Flying Corps soars free of the confines of alien gravity, where the true scale of the planet’s mystery is revealed. To uncover the truth, however, he must join forces with an unexpected ally.