Lydia Cavanaugh lived alone in a small cabin on the edge of an ancient redwood forest, her nearest neighbor separated by several miles of unpaved switchbacks and moss-strangled undergrowth. The isolation suited her: She had never been comfortable with the easy warmth of small talk, or the way most people seemed to expect a constantly performed, smiling self.

Instead, Lydia preferred the company of lichens, mosses, and the minute ecosystem of her hydroponic tanks, each one engineered to maximize output with as little intervention as possible. She was a brilliant scientist?a botanist and systems engineer with a rare, almost preternatural talent for seeing patterns in chaos?but struggled to see herself as anything but plain.

Her stringy brown hair and oversized glasses hid a face that colleagues sometimes called "interesting," as though that word could serve as a polite cover for "awkward." Even her gait, a result of a childhood injury, was slightly off-kilter, and she tried not to mind when people commented on it.

It was a cold, clear evening in November when Lydia first saw the light. She was cataloguing fungal samples under the microscope in her living room, sipping at a mug of reheated coffee, when a faint, otherworldly glow flickered at the corner of her vision. She looked up, squinted through the condensation-streaked glass, and saw a streak of silver-blue arcing low across the treetops.