The Army of the Night

It's 1813. Napoleon's army needs to retreat from Spain and return to France, but the main pass across the jagged peaks of the Pyrenees is within easy reach of the British forces.
In his search for an alternative escape route, Alaine Bellanger discovers more than just an ancient mountain trail. High up, in a cleft between two peaks, he finds something very strange indeed — and someone even stranger.
But who can he tell?
And who would believe him?