In the far future, humans share their world with the feline race of the sphinx. D'Artagnan, a young loner, dreamer, and gadget master, lives a quiet life with his scientist uncle. Until the day he meets Rissa, an attractive girl sphinx of his age who's more than a match for his rebellious, smart-aleck ways.

But even as the two grapple with feelings they've never experienced before, they stumble across a villainous plot to kidnap a genetically engineered racehorse! Can Rissa and D'Artagnan foil this evil plan? Come to think of it, can they pull it off without killing each other? All bets are off in the world of Sylph!