Hannah Witheridge and David Miller are perfect strangers who hail from coastal towns in the UK. They both decide to take a backpacking trip to Thailand before pursuing Master's Degrees in their respective fields. These two kindred spirits meet for the first time on the small island of Koh Tao. The island is a tropical paradise. Its' waters teem with scores of fish and wildlife. It's a romantic idyllic setting, and the young pair hit it off immediately. But something sinister is lurking in the shadows, and this budding romance ends in a horrific tragedy that shocks the global community.