In 1999, radiologist Nicola Strickland went on a holiday to the Caribbean island of Tobago, a tropical paradise complete with idyllic, deserted beaches. On her first morning there, she went foraging for shells and corals in the white sand, but the holiday quickly took a turn for the worse. Scattered amongst the coconuts and mangoes on the beach, Strickland and her friend found some sweet-smelling green fruit that looked much like small crabapples. Both foolishly decided to take a bite. Within moments the pleasantly sweet flavor was overwhelmed by a peppery, burning feeling and an excruciating tightness in the throat...