The depths of winter. Clement and Bosco are underage volunteers in the Resistance, fighting an alien invasion. Bosco is given charge of the 'battle book', a manuscript believed to have protective powers. The youngsters accidentally initiate engagement and a fragile ad hoc cessation of hostilities when they stumble into one of the aliens' encampments.
A side-story to the Hibernia Altera sequence, set some centuries before the novels. It is included in the collection Fluctuation in Disorder.