The series tells the true story of the Milperra massacre, when the Bandidos and the Comancheros motorcycle clubs went to war on Father's Day, Sunday 2 September 1984. The massacre had its beginnings after a group of Comancheros broke away and formed the first Bandidos Motorcycle Club chapter in Australia. This resulted in intense rivalry between the two chapters. At a public swap meet at the Viking Hotel at Milperra, a brief but violent battle ensued with seven people shot dead, including a 14 year old innocent bystander. A further 28 people were wounded with 20 requiring hospitalisation.