Who is Petrus, this amiable redhead who appears out of nowhere in the cellar of the Castillo where Alejandro de Yepes and Jesús Rocamora, young officers in the Spanish regular army, are stationed? Petrus exudes magnetism and a mysterious aura. Alejandro and Jesús are bewitched, and, in the middle of the sixth year of the longest war humankind has ever endured, they abandon their post to follow him across a bridge they cannot see.

Petrus’s world is one of lingering fog, strange beings, poetry, music, natural wonders, harmony and extraordinary beauty. It is also where the fate of the world we recognize as our own, and all its living creatures, is decided. Yet it is under threat. A long conflict with the forces of disenchantment is drawing to a climactic close. Whether poetry and beauty will prevail over darkness and death, and what role Alejandro and Jesús will play in all of this, lends suspense to Muriel Barbery’s new richly imagined novel about a world facing annihilation.