To her owners, apartment-dwellers on the upper East Side of New York's Manhattan Island, Rhiow looks like nothing more than their little black pet cat: a sweet-tempered, good-natured little creature who shakes them down for food at every possibility, is always ready for a cuddle, and never ventures any further away than the apartment's terrace.
But a lot more could be said about Rhiow... for when her humans aren't looking, she has a life of her own that they don't dream of. Rhiow is a wizard, and heads an elite team of other feline wizards whose job is to keep the Grand Central worldgates running. With her teammates Urruah (a dumpster-living, foodie tomcat with a yen for opera) and Saash (the "Scotty" of their team, cerebral and witty, but always scratching at fleas that aren't there), they help keep the city's wizardly public transport system purring along.
...Until one morning matters get suddenly complicated with the arrival of Arhu, an abrasive feral tom-kitten in the middle of his Ordeal – the potentially deadly initiation through which every wizard must pass to come into his or her power. The chain of events triggered by Arhu's adoption into their team leads Rhiow and her companions out of their own New York and into another, more ancient, and far deadlier one – to a confrontation with the Lone Power that's intent on the destruction of cats and humans alike.
There, Rhiow and her team must deal with not only the sudden danger wound together with Arhu's fate, but a terrible secret concealed in the heart of the feline underworld, ready to burst out in annihilating force into the world of men, which as wizards they're sworn to protect. Now the cat-wizards' only hope of success lies in their uneasy bond with a race of creatures who've been their enemies for all time – and now hold the key not only to their own survival, but that of the human race...