As Winter Knight to the Queen of Air and Darkness, Harry Dresden, Chicago's only professional wizard, never knows what the scheming Mab might do ... and she's just traded Harry's skills to pay off a debt. Now he must help a group of supernatural villains -- led by one of Harry's most dreaded enemies -- access the highest-security vault in the Nevernever to recover the literal Holy Grail from the vaults of Hades, Lord of the freaking Underworld.