Bill Nye hosts this survey of competing scientific theories about how life on Earth began. The film opens by clearing up misconceptions about bacterial sludge, the mats of microorganisms often cited in origin-of-life discussions, before moving to the ocean floor to look at chemosynthesis, the process by which deep-sea organisms build energy from chemicals instead of sunlight near hydrothermal vents. From there it turns to three rival explanations for life's spark: comets seeding the planet with organic material, volcanic activity providing the necessary heat and chemistry, and an explosion described as more powerful than all combined nuclear forces on Earth. Nye walks through the evidence behind each theory rather than declaring a winner, treating origin-of-life science as an active argument among researchers rather than a settled question. The film stays close to its host's explanations throughout, using him as the connective thread between bacteria, deep-sea vents, and planetary-scale catastrophe as possible starting points for evolution.