After a traumatic encounter with a 30-ton humpback whale that breached and almost landed on him while he was kayaking, filmmaker Tom Mustill was haunted by the question: was the whale deliberately trying to hurt him or trying its best not to? After investigating with whale experts and those who have survived similar close encounters, what he discovers raises far bigger questions about humans' relationship with whales and their future.

Watch it tonight at 8:30pm on WGBH World