For the past eight months, Kate had been working as a lab researcher for Dr. Grant Packer, up at Albert Einstein Medical College in the Bronx, whose work in cytogenetic leukemia was starting to make noise in medical circles. She’d won a fellowship out of Brown, where she and Tina had been lab partners her senior year.

Kate was always smart-just not “geeky” smart, she always maintained. She was twenty-three. She liked to have fun-hit the new restaurants, go to clubs. Since she’d been twelve, she could beat most guys down the hill on a snowboard. She had a boyfriend, Greg, who was a second-year resident at NYU Medical School. She just spent the majority of her day leaning over a microscope, recording data or transcribing it onto digital files, but she and Greg always joked-when they actually saw each other-that one lab rat in their relationship was enough. Still, Kate loved the work. Packer was starting to turn some heads, and Kate had to admit it was the coolest option she’d had for a while.

Besides, her real claim to distinction, she figured, was no doubt being the only person she knew who could recite Cleary’s Ten Stages of Cellular Development and had a tattoo of a double helix on her butt.

“Leukoscopophy,” Kate explained. “Pretty cool the first time you see it. Try watching it a thousand times. Now check out what happens.”

They leaned back over the double scope. There was only one cell left-larger, squiggle-shaped Tristan. The defective lymphoblast had virtually disappeared.

Tina whistled, impressed. “If that happens in a living model, there’s got to be a Nobel Prize in this.”

“In ten years, maybe. Personally, I was just hoping for a graduate dissertation.” Kate grinned.

At that moment her cell phone started to vibrate. She thought it might be Greg, who loved to e-mail her funny photos from rounds, but when she checked out the screen, she shook her head and flipped the phone back into her lab coat.