In 1983 a gang of armed robbers hijacked a security depot near Heathrow Airport and held the guards to ransom expecting to steal cash in the region of £3 million pounds. But their operation didn’t exactly go according to plan. Security guard Robin Risely couldn’t remember his part of the codes to the safes and remarkably the gang stumbled on a much bigger prize - £26 million of gold bullion. The hunt for the gold was one of the biggest the world has ever seen. The thieves had it smelted down and resold into the market. Now, in this new documentary we hear first hand accounts from the security guards who were on shift that fateful morning and officers on the case.