The Gas Man

It starts with a tip-off. It's the late 1980s and US Special Agent Dennis Bass is warned about a shipment of suspicious chemicals headed to a secret destination. So he follows the lead – and ends up stumbling into a global plot helping fuel a war. The main suspect? The Gas Man. In the decades since, Special Agent Bass has been locked in an international game of cat and mouse with the man who supplied a dangerous regime with the chemicals to make weapons. Every time Bass thinks he's got his hands on him… The Gas Man somehow manages to slip the net. And he's still on the run today. But after more than 30 years, could his past finally be catching up with The Gas Man?

In the 1980s Special Agent Dennis Bass received a tip-off that changed the course of his career. 30 years on reporter Chloe Hadjimatheou sets out to solve the mystery of how an international fugitive got away with his crimes – and why he's still on the run.

Special Agent Bass has his target in his sights but he's on another continent. If he wants him to talk he'll need a clever plan – and maybe a bit of luck.

The team persuades The Gas Man to step out from the shadows. He reveals the first big clue in the investigation to how he got away with it – and makes a surprising claim about his role in the case.

Chloe makes a startling discovery about another chemical trafficker that has consequences for her investigation. A Kurdish survivor of mustard gas shares her story

In this episode, Chloe looks into what happened to The Gas Man when he arrived back in Germany as a fugitive – and investigates whether his trade with Iran ever really ended

In the last episode of the series, is the 40-year cat-and-mouse game nearly over?