One of the most shocking people smuggling cases ever to hit UK soil features in a BBC Two documentary, Hunting the Essex Lorry Killers.
It delves into the investigation by Essex Police which spanned the UK, Europe and Vietnam and uncovered an extensive crime network that proved deadly for 39 migrants.
Take a look at the true story behind the case which shocked the nation in 2019.
When is Hunting the Essex Lorry Killers on TV?
The documentary will air on BBC Two on Wednesday, 13 October at 9pm.
What was the Essex Police case about?
In October 2019, a shocking story hit the headlines when an HGV driver discovered 39 dead Vietnamese migrants in a container on his vehicle.
However, the story was set to become much worse when Essex Police, suspicious that the driver didn't seem to be particularly upset, started to question his claims that he'd had no idea they were there.
It soon became clear that the driver was in fact a part of a much larger people smuggling ring that saw him and his co-conspirators facing manslaughter charges.
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Police could prove his involvement through phone records and CCTV footage, with the investigation uncovering a multi-million-pound, international operation that was being run from a haulage business in Northern Ireland.
The 39 victims of the tragedy had travelled from Vietnam after being promised a better life in the UK, but were never to make it out of the lorry as they suffocated in the container on its journey by sea between Belgian port Zeebrugge and Purfleet.
BBC Two's documentary takes the time to visit the grieving families in Vietnam who talk heartbreakingly of their terrible loss and the dream of a new life that their loved ones had been sold.
Some of the migrants were just 15 years old, and an investigation into their journey showed how they had tried in vain to break through the roof of the lorry with a metal pole.
Phone messages between the driver and his smuggling ring boss showed that he had been told "give them air quickly don't let them out", at which point the driver had discovered that none of the 39 had survived the ship's crossing.
What happened to the smugglers?
At the smuggling gang's trial, judge Mr Justice Sweeney summed up the severity of their crimes: "I have no doubt that the conspiracy was a sophisticated, long-running and profitable one to smuggle mainly Vietnamese people across the channel."
He added: "There were desperate attempts to contact the outside world by phone and to break through the roof of the container.
"All were to no avail and, before the ship reached Purfleet, they all died in what must have been an excruciatingly painful death."
Four men were convicted of manslaughter, including lead conspirators Ronan Hughes and Gheorghe Nica who were sentenced to 20 and 27 years respectively.
Eamonn Harrison, who towed the container to Zeebrugge, was given 18 years, and Maurice Robinson, the HGV driver who collected the trailer at Purfleet and discovered the bodies, got 13 years and four months.
Three other members of the gang were sentenced for conspiracy to facilitate unlawful immigration.
Watch: Migrants tell of risky journeys crossing Channel