Like many biotech companies, Ablynx emerged from the confluence of a serendipitous discovery, an open window of opportunity and an unreasonable ambition. Housed on two floors in a nondescript gray laboratory on a technology campus outside the university town of Ghent, Belgium, the three-year-old company employs just 45 people, 33 of them scientists and bioengineers. It is a minimal staff with a simply stated mission: find the tiniest sliver of protein that will do the job of a full-size antibody, then turn it into a billion-dollar medicine--or better yet, into the first of a whole new class of "nanobody" drugs against cancer, rheumatoid arthritis, inflammatory bowel disease, perhaps even Alzheimer's disease.