A year earlier, during her morning run, Gina had picked up her pace. She was speeding along when she screeched to a halt, kicking up dirt like in a cartoon, seven feet shy of a fer-de-lance. The pit viper was the deadliest snake in South America, responsible for more than a hundred thousand deaths a year. Luckily, the snake only gave her a quick assessment, then slithered into the brush.

It was a healthy reminder that in the jungle you had to be vigilant.

For better or worse, Gina had been conditioned for vigilance at a young age. Her mother had died when Gina was five years old, and she was raised by a single father. A single, military father. Throughout her early childhood, Gina followed her father to seven military bases on three different continents. In addition to her daily school load, her core curriculum included combat lessons, threat assessment, and weapons safety.

Finally, after a promotion, William Brady and Gina found a home at Marine Corps Headquarters in Arlington, Virginia. Jumping from military base to military base had made it difficult for Gina to make long-lasting friendships, but within a few weeks, when a young freckled boy moved onto base, Gina made her first real friend.

Paul and Gina were inseparable, and a few years later, on Gina’s sixteenth birthday, that friendship blossomed into fiery passion. The two dated throughout high school and undergrad at the University of Virginia. After undergrad, he went to Georgetown to get his MBA in political science; she stayed at UVA and started med school. After a year doing long distance—which wasn’t all that long, it was only a two-and-a-half-hour drive—Paul called it quits.

Crushed, Gina put everything into her studies. She graduated from med school, aced the MCAT, and cruised through her first three years of residency. There were flings, of course, but it was always physical. Nothing more. A means to an end. Then, in the last year of her residency, Gina’s father died in a car crash. At the funeral, she saw Paul for the first time in years. He had a redhead on his arm, and she was brandishing the engagement ring that, even after their break-up, Gina had always envisioned on her finger.

Parentless and broken, at the age of thirty Gina needed a change, and she applied to the World Health Organization (WHO). Her first posting was to Romania, where for two years she bounced around, treating different rural communities. When there was an outbreak of tuberculosis in Bolivia, Gina jumped at the opportunity to move to South America. With her background in infectious disease and four years of college Spanish under her belt, she was a perfect candidate. A week later, she and a team of two other doctors made the exhausting journey into the dense Amazon rainforest and to the remote village of Tibióno.