Four Corners exclusively brings you the story of the Sharrouf children and their grandmother's epic fight to find them and bring them home to Australia.If there was one family that represented the alarming tide of Australians flocking to the black flag of Islamic State, it was the Sharroufs.Reporter Dylan Welch and producer Suzanne Dredge have documented the family's experience for four years, travelling with the children's grandmother as she tries to convince the authorities in Syria and Australia to release the family into her care and allow them to return home.