On the fringe of a large forest, up a road swallowed by foliage, sits a smiling purple unicorn—pastel purple, to be exact—capping a sign that reads: Martha MacGuffie, Plastic Surgeon. Martha MacGuffie, MD, 82, has herded 740 unicorns—figurines, doorstops, designs on stained-glass windows—across her sprawling estate 35 miles from New York City. The fairy-tale-like HIV activist lives and works in a replica of a Scottish castle, and today she stands outside it, a tiny bespectacled woman in an oversize blazer, gathering stray branches. “Unicorns are protectors of all creatures,” says MacGuffie, who has lost three sons to AIDS. “People always give them to me.” She speaks comfortingly, like a good doctor, with measured intensity, her hands knobby and wrinkled but rarely still. Quite a protector herself, she mothers five surviving daughters (like her, all negative) and nurses injured raccoons, dogs and horses outside the castle, while performing human reconstructive surgery within its walls. The castle also houses the Society for Hospital and Resources Exchange (SHARE), which MacGuffie founded in 1987. SHARE provides health and other aid in the Suba region of Kenya, where the HIV infection rate is 40%.

Twice a year, she travels to Kenya with SHARE workers, returning just before the height of malaria season. SHARE, which has raised hundreds of thousands of dollars in private donations and grants, not only builds clinics and treats patients but also provides education, nutrition and tools, such as solar-powered ovens, to help villagers take charge of their own health. Additionally,  SHARE sponsors orphans, sometimes sending them stateside to get a college education. “We treat Kenyans with medication, and we give them hoes, plows and donkeys,” says MacGuffie. “Even if they have AIDS, they can get healthy and farm and sell the food and take care of themselves and their families.” The villagers call her Domtila Awiti, which in the regional dialect Luo means “grandmother picking up children by the side of the road.”

At the age of 5, MacGuffie determined that she would pursue a medical career, like her father, eventually becoming one of the first women to graduate from Columbia University Medical School in 1949. She had her eight children with two husbands; the two youngest boys, Reed and Rob, were born with a rare hereditary blood disorder that caused a severe form of anemia. After receiving a series of blood transfusions in 1979, the boys began to develop mysterious ailments. Reed died in 1980 at 13 and Rob in 1982 at 17. “No one knew what it was at first, but it was AIDS,” says MacGuffie. “And then the oldest boy, William, who was 19, fell apart completely and got involved in drugs and alcohol.” She says he disappeared in the mid-1980s, occasionally calling home for money. “During one of his last calls he said he couldn’t give blood anymore because it wasn’t any good, so you can piece together what happened, that it was AIDS. We looked for him for eight years, but we never found him.” She founded SHARE, she says, “because when I discovered the boys had AIDS, I wanted to find the place where it was the worst. It made me feel better. Also, [the Suba region] is where Louis and Mary Leakey discovered the remains of the forerunner of man. I wanted to go to the place where human life began.” So in her sixties, when a mother of eight and an accomplished surgeon might be expected to retire to Lake Placid, MacGuffie took off for Lake Victoria. “I worry about her going to the train station, much less Africa,” says her youngest daughter, Pamela Hudson, 49. “But she’s not exactly the type of person you tell to slow down.”

MacGuffie has also worked with AmeriCares, treating refugees in Zambia, Rwanda and other African countries. Keith Rosario, who works with MacGuffie recalls one such trip: “There had been gunfire all night, and we didn’t have any water at the refugee camp. Suddenly, we noticed Martha was gone, and we started searching frantically. Just then she shows up with a convoy of U.S. military vehicles bringing water. She had walked three miles alone in the middle of the night, risking kidnapping, and found some three-star general.” Hudson says of her mother, “She has a great sense of timing. I wasn’t there, but CBS came to Kenya to film her for 48 Hours. All of a sudden, someone brings this guy out of the bush who has been hacked by a machete, and she saves his life right there on camera. I was like, ‘Did someone call central casting?’ ”

On the first floor of MacGuffie’s castle, down a cavernous corridor, are several rooms set up to treat patients. The walls are covered with snapshots of people she has treated around the world—most are children. Outside, there is a stable with horses and a bell from the battleship USS Maine, as in “Remember the Maine.” About ten feet away, by the entrance to her office sits a stone statue of a young boy wrestling an alligator, marking where she buried her sons’ ashes in the yard. Will she ever retire? “Technically,” she says, “I’m retired now. I did that at about 50.”

To learn more about SHARE or to donate, visit www.shareafrica.org.