Hi, it's Kara here. Thank you for returning to Bed of Lies. I just wanted to let you know that

telegraph subscribers can binge this series of Bed of Lies now. Click on the link in the show notes

to find out how to connect your Telegraph subscription with Apple Podcasts. On the shores of Belfast Lock, there's an old tobacco factory.

It's 11 miles from Belfast City Centre in a town called Carrick-Fergus.

This sprawling 17-acre compound is hidden behind high walls that are fortified with barbed wire.

Officially, it's called Sea Park, but one source tells me he calls it the edge of darkness,

because everything here feels black, from the deep waters of the lock to the capes and guns of the guards.

Somewhere in the bowels of sea park is the vault, a store of millions of classified documents

that together tell the history of the troubles in Northern Ireland.

Evidence of kidnaps, murders, bombings and collusion.

It's meant to be an impenetrable fortress.

This was the most secure place in Northern Ireland, allegedly.

At the beginning of 1990, Detective John Stevens is running a sensitive investigation here,

looking into a string of controversial killings.

I had my own office at one end, and then we had a kind of storage place where very secure papers were.

Northern Ireland's riven apart. Armed groups have been clashing violently for more than 20 years.

Catholic Republicans on one side,

Protestant Unionists on the other, all over whether the country should stay part of the United

Kingdom. It was an extremely hard, harsh environment. Four months into his investigation,

John Stevens has gathered enough evidence to arrest a network

of unionist fighters for the murders he's looking into. The operations plan for 6am, and

he's in his hotel room trying to relax. He has a bath and gets ready for bed. But just as he's

...