Synopsis: Harpy eagles are the most powerful birds of prey in the world. Standing three feet tall, with a six-foot wingspan and razor-sharp talons the size of bear claws, these birds are the heavyweight hunters of the South American rainforest. But scientists know very little about harpy eagles because their numbers are few, their habitat is large, they never soar above the trees, and they rarely come to the ground. Nature enters their secret world with wildlife filmmaker Fergus Beeley.