Edith Widder grew up determined to become a marine biologist. But after complications from a surgery during college caused her to go temporarily blind, she became fascinated by light as well as the power of optimism. Her focus turned to oceanic bio-luminescence, a scientific frontier, and with little promise of funding or employment she took a leap into the dark. 'Below the Edge of Darkness' explores the depths of the planet's oceans as Widder seeks to understand one of the most important and widely used forms of communication in nature. In the process, she reveals hidden worlds and a dazzling menagerie of behaviours and animals, many never-before-seen or, like the legendary Giant Squid, never-before-filmed in its deep-sea lair.