One night the painted wolves began to sing. It was something that few people had ever heard, let alone recorded. The director fumbled for his phone, switched it on and captured one of the most haunting sounds ever to come from the African wilderness - the keening melody of a pack of wild dogs, or painted wolves as they are better known, honouring their new alpha.
Those who have spent time with these animals will know the excited yipping and yelping a pack makes when they are feeding, hunting or greeting one another. But the singing? That was a revelation, not least of all for the film crew.
For them it was a startling gift to mark the end of a three-year odyssey, during which they had witnessed the fall and rise of a pack of these deeply misunderstood canines.
The pack had been competing with their own kind for new territory in a sprawling wilderness on the south bank of the Zambezi River. In that time, a daughter had turned on her mother, sparking a struggle that was every bit as epic as a war between humans...