The Sundered World (Paperback, New edition)

In the violent streets of a despoiled London, Alan Duval is wounded by the poisoned blade of a ceremonial dagger. His life is saved by a mysterious feral girl. Then, suddenly, bewilderingly, he is transported from Earth to a mirror world - Tir - in which he encounters a darkly comic creature, Granny Ddhu. Treating his wounds, she confers on him the Oraculum of the Tridedana, the gateway to immense power and the first step in a seemingly impossible quest. The spiritual continent of Monisle has been at war for a thousand years with the forces of darkness. Duval must use his powers to defeat the Tyrant of the Wastelands. The survival of Earth as much as war-ravaged Tir depends upon his success.