The Devil's Looking-Glass: The Sword of Albion Trilogy Book 3

Synopsis

1593: The dreaded alchemist, black magician and spy Dr John Dee is missing...

Terror sweeps through the court of Queen Elizabeth, for in Dee's possession is an obsidian mirror, a mysterious object of great power which legend says could set the world afire.
And so the call goes out to celebrated swordsman, adventurer and rake Will Swyfte - find Dee and his feared looking-glass and return them to London before disaster strikes. But when Will discovers the mirror may help him solve the mystery that has haunted him for years - the fate of his lost love, Jenny - the stakes become acutely personal.
With a frozen London under siege by supernatural powers, the sands of time are running out. Will is left with no choice but to pursue the alchemist to the devil-haunted lands of the New World - in the very shadow of the terrifying fortress home of England's hidden enemy, the Unseelie Court.
Surrounded by an army of these unearthly fiends, with only his sword and a few brave friends at his back, the realm's greatest spy must be prepared to make the ultimate sacrifice - or see all he loves destroyed.