Bedfordshire Police investigate banging coming from inside a refrigerated HGV lorry that recently passed through Dover after crossing the Channel. Inside, they find a three-year-old girl, her five-year-old sister and their mother, as well as 12 other migrants who have been smuggled into the UK. The police now face a race against time to ascertain whether they have been illegally trafficked into the UK and deliberately imprisoned in the refrigerated container for more than 17 hours, or whether they have smuggled themselves aboard the lorry without the knowledge of the driver or transport company