Geneticists Clive (Adrien Brody) and Elsa (Sarah Polley) specialize in creating hybrids of species. When they propose the use of human DNA, their pharmaceutical company bosses forbid it, forcing them to conduct experiments in secret. The result is Dren, a creature with amazing intelligence and physical attributes. At first, Dren exceeds their wildest dreams, but as she begins to grow at an accelerated rate, she threatens to become their worst nightmare.