Sixteen-year-old Sep stares into the bathroom mirror. It’s not some weird lipstick (she never wears lipstick). Her lips are just — white. In a panic, she digs up an old lipstick and smears it on her colorless lips. But soon, more and more white spots begin to bloom, spreading their chalky tendrils across her olive brown skin. Does she have a disease? Is she turning into some kind of freak?

Sep is usually the one who knows all the answers. With a quicksilver mind and a supple body, she’s happiest when she’s delving into the mysteries of animal biology or giving herself over to sweet, hot moves in Jazz Dance Club. Unlike her best friend, Devin, she’s never been in a rush to get a boyfriend. But as the white blotches spread, her dating days — like the endangered species she studies — seem numbered. So when Joshua, a boy she’s always liked, makes a flirty advance, she wonders: why not grab pleasure while she can?