Dr. Navarre beckoned me toward an experimental apparatus: a large vat about the size of a wine barrel, filled with a milky white liquid, with a small platform in the center just below the surface. In the experiment, the mice were allowed to splash around until they found the platform. Normal mice remembered how to find it, but those with severed brain pathways were lost. They had to search for the platform randomly each time.

“So we gave these poor mice our treatment,” Navarre explained, “and after several months, their memories returned, every one. Here, I will show you.”

Navarre brought a cage containing one of the treated mice to the table. He opened the cage door, removed the mouse and placed him gently on the edge of the vat. The mouse swam very deliberately toward the hidden platform. When this first mouse was safe on its perch, Navarre took him back to the cage and plucked another, who performed the test just as well, then repeated it with a third. “You see!” he said when the last mouse was back in the cage. “They are cured.”

“How did you do it?” I asked. I wanted to be interested. I wanted to listen to this cloistered little man all afternoon, and then write a story about how his mice would change the world. I didn’t want to slip back into ordinariness.

“We gave them a substance called a neurotrophin—a nerve-growth factor—which allowed the severed brain pathway to rebuild itself. This is my cure.” He explained the basic science for me. Neurotrophins were the essential tools of the nervous system. They fed the axons in the brain and spinal cord: without neurotrophins, the axons died; with them, even the axons of a severed spinal cord could grow and regenerate. But the brain had a horrible counterpart to these neurotrophins. They were known as “suicide genes,” and they destroyed brain cells and their connections. That was what made Alzheimer’s disease so debilitating, according to Dr. Navarre. But a treatment that could get the life-giving neurotrophins into the brain might rebuild the damaged pathway, and cure Alzheimer’s.

I was nodding, but my concentration had been interrupted. Out in the corridor someone was shouting. A door opened at the other end of the lab, and a security man summoned the press officer. He scurried away, leaving me alone with Dr. Navarre.

“But how did you do it?” I asked again. “How did you get the neurotrophins into the brain? I thought there was a barrier that blocked things from getting in.” In reading my crib sheets over the past twenty-four hours, I had discovered something called the blood-brain barrier, which allowed glucose and some proteins to enter, but prevented passage of most other substances. That was why doctors found it so tricky to treat some brain diseases with drugs.

“This is my discovery,” said Navarre quietly. “I have found a chaperone, which can escort the neurotrophins into the brain.”