It was a story that left the world holding its breath. The search for the Titan sub sparked an international rescue operation and gripped public attention across the globe. In this exclusive two-part documentary we examine, minute by minute, the race against time to try and save five people on their doomed dive to the wreck of the Titanic. In a world first, we reveal exclusive audio from the frantic global rescue operation that ultimately ended in tragedy, leaving everybody onboard dead. But why did this extraordinary expedition go so terribly wrong?