Three hundred million homeless cats hide in our cities. Most don't survive beyond a thousand brutal days of starvation, disease, and death as prey. When Princess Rosamonde Whitewhiskers, born a purebred Abyssinian in an upscale cattery is dumped, she faces the slow painful death of the abandoned. But Great Mother has a plan, and Rosie is saved by a clan of ferals who take her to their home in the Green. They believe she is the 'discarded queen' who must be found to fulfill a Prophecy – a promise the holocaust visited upon her species by man will end. In their world as in ours, animal homelessness is a crime and death the only punishment.

Rosie adapts to survive in the strange forests, marshes and canyonlands of spirit cats, and feline shamans. She learns that eastern clans are psychics, southern cats are seers, western kin are empaths, and her new friend Ghost, a natural healer from the north, must master everyone's magic to save them. Will the kin succomb to the forces bent on their destruction: the White Truck, the Ghostdogs, and a twisted wizard cat who wants to rule them all? Will they rally, work through their differences, learning from their obstacles that love is the only real answer?

Rosie must return to her human to fulfill her part of the Prophecy. She and her troupe are relentlessly pursued by the coyote Grimfang and his new allies, including an abandoned, disillusioned mutt named Grip, and Fleazor, a monstrous sewer rat. In the Green, Ghost battles an evil sorcerer cat, while Bigpaw forges an alliance with Roak, a young raven. The clans of the four elements must work together to overcome the forces that would eradicate them, but who can herd cats?