A mysterious mutation is affecting random children in The City. They become human/animal hybrids at some point in childhood or adolescence. While females get off with a few extra appendages (ears and tails mainly), males are deformed into twisted abominations and die shortly afterward. After too many sons lost this way and no cure found, the majority of unaffected humans are against all hybrids and the city has special forces hunting them down for extermination.

The hybrid girls and women live in hiding to protect themselves, relying on the minority of human sympathizers to shelter and care for them. Some men marry hybrid women, and the mutation is weaker in their children. The girls evolved the ability to retract their animal traits temporarily; the boys no longer melt into hamburger but occasionally revert to animal intelligence.

In one such family are two were-hybrid sisters. Doggirl big sister is strong and friendly and looks out for everyone; she hopes to get into showbiz and win human hearts and minds so that someday hybrids can reintegrate with humanity. Catgirl little sister is a stylish, mischievous, adventurous loner, who is happy living apart from humans and just taking care of herself.