Spanning Britain, Europe and Vietnam, this film shows how detectives cracked open a multimillion pound international smuggling ring with its roots in a seemingly innocuous haulage business in the heart of Northern Ireland. With exclusive access to Essex Police, their officers and the evidence, the documentary reveals how detectives painstakingly pieced together a complex web of evidence, including the extraordinary role of a witness known only as 'Witness X', whose evidence helped bring down the gang. The film also travels to Vietnam to meet the families of some of those who died in the back of the lorry, hearing their heartbreaking stories of losing loved ones on the false promise of a new life in the UK. Together, this forms an account of one of the UK's most shocking crimes and a story that lifts the lid on the hidden world of organized crime's trade in people smuggling.