Monterey Bay, located along the central coast of California, is a frontline of deep-sea biological research. Here we’ll take a glimpse into the mysterious world of the curious life forms with luminous bodies and their predatory enemies that have survived the harsh, pitch-dark marine environment that quietly lies off the U. S. Pacific coast at the depths of 200 to 1,000 meters — a region called the “Twilight Zone”. An enormous canyon equivalent in scale to the Grand Canyon lies beneath the waters of Monterey Bay.

As the crew dives in manned submersibles, together with Bruce Robison, an enthusiastic marine biologist who has long surveyed the area and Edith Widder, an expert in bioluminescence of oceanic life, they encounter a spectacular light show at the deep fathom of our planet.