The DLR platform is full of smartly dressed bankers, laden down with bags of Christmas gifts from the shiny shops of Canary Wharf. They gleam with the patina of money and success. I look down at my scuffed trainers and make a mental note to buy some new shoes.

A thin layer of snow is covering the pavement when I walk from Poplar station to Aunt Peg’s flat, past pinched-together terraces and estates with broken windows. Two teenagers laugh and bump my shoulder as they walk by, their faces lost inside the cavern of their hoods.

On the stairwell, there’s the neck of a glass bottle. A screaming argument from somewhere in the tower block echoes down the concrete corridor. The estate’s signature perfume of piss fills my nostrils.

‘Only me, Aunt Peg,’ I shout over the television as I let myself in.

Technically, she’s my great-aunt, my late grandmother’s sister. But when my mother died and I could not stand to be near my father, she was the only family to offer me a place to live. At a time when the foundations of my life were shifting beneath my feet, she provided a bedrock of stability. Now she’s eighty-four and needs a bit of extra help, and with the cost of London living, I haven’t quite got around to moving out yet. As far as I’m concerned, Aunt Peg is my family now.

From my bedroom window, I watch the triangle of Canary Wharf blink in the distance and wonder, not for the first time, how I can make my mark at the newspaper.

As the trains grind through the snow and the city is pinpricked with thousands of lights, a voice in my head whispers to me. The answer, it says, lies in the shoebox stuffed at the bottom of my cupboard. The faded photographs of the Carter family. Three or four pencil drawings. A few handwritten letters forwarded from the secure children’s home in the weeks and months after the trial.

This collection of memorabilia from one of the country’s most shocking murders in living memory would bring me to any editor’s attention. Multiple front-page exclusives. Syndicated around the world.

But there’s a reason I’m reluctant to reveal my connection to the Carter family, and it’s not just because I don’t want my photograph in a national newspaper. The truth is, I know more about these killings than the police ever did. Many years ago, I boxed up that knowledge, packed it away and labelled it DO NOT OPEN. But it’s haunted me ever since, colouring everything with a shade named guilt.

If I write the defining story of my career – and it will define me, I’m certain of that – it will open a Pandora’s box.

The trouble is, once the lid’s off, there’ll be no going back.

6

It was completely dark outside.