Lindsay is a friendly, adventurous young woman with an endless curiosity for trying new things. One weekend she'll be hiking a mountain trail, the next taking a boxing class, learning to golf, trying indoor climbing, or going somewhere simply because she's never been there before. She's quietly confident, makes conversation with strangers as though they've been friends for years, and is equally comfortable dressed for a formal evening or wandering around in shorts and sneakers with no particular plan.

The unusual part is that Lindsay is, quite literally, two-dimensional. From the front she resembles an illustrated woman outlined against the world around her; turn her sideways and she nearly disappears. Nobody has a particularly good explanation for how this works, including Lindsay, and the geometry involved becomes increasingly uncooperative if examined too seriously. She eats, sleeps, works, wears clothes, picks things up, and occupies the three-dimensional world perfectly normally despite possessing a body that apparently declined one of its spatial dimensions.

Lindsay rarely thinks of herself as unusual unless circumstances remind her. She catches the wind spectacularly, has learned to respect ceiling fans, enthusiastic dogs, and anyone holding open scissors, and occasionally discovers practical problems nobody else has ever needed to solve. None of it bothers her much. As far as Lindsay is concerned, she's simply living her life like everyone else. The laws of geometry are the ones making it weird.