Rhiow, Urruah, and Arhu, the wizard cats who saved New York City in Diane Duane's The Book of Night with Moon, are summoned to London to deal with a crisis in the very fabric of time. Their old nemesis, the evil Lone One, is manipulating an alternate universe to unleash nuclear destruction that will spread across the dimensions. Aided by a 15-year-old Arthur Conan Doyle, the feline heroes must save the life of Queen Victoria -- every Queen Victoria in every universe -- and find the forgotten magic needed to restore the correct course of time...before they cease to exist. And that would be a cat-astrophic outcome indeed.