That night, Dee barely slept. Each time she closed her eyes, her mind raced off in multiple directions, trying to make sense of everything. As the first fingers of grey light started creeping into her bedroom, she gave up on sleep and got up, groggy and grumpy. Over a pot of coffee, she made a plan. She was going to go back to London to find Annie, and she wasn’t leaving until she got some answers to the questions that had kept her awake during the long night.

An hour later, she was at the train station. Even on Saturday, the price of a return ticket to London was jaw-droppingly expensive. At least, Dee consoled herself, taking the train was faster and less painful than driving into the city.

Following her long conversation with Emer on the phone last night, Dee had sat down on her sitting room floor with a sheet of A3 paper, creating a mind map that gradually filled the page. This was how she’d always liked to work. Noting down everything she knew about a story. Then, once she had all the facts written down, she was able to see the bits of information still missing.

The facts were easy enough. On 5 June 1997, Lucy Ryan said good night to her parents and went to bed. The following morning, when Lucy’s mother went to wake her daughter, Lucy’s bed was empty. Her daughter was gone. To this day, Lucy’s sister, and the Guards investigating her disappearance, didn’t know what had happened to her.

Three weeks later, on 27 June 1997, Kitty Doran disappeared, supposedly drowning in the sea while on holiday with her family in the west of Ireland. Her body was never discovered but a coroner’s inquiry concluded that Kitty had drowned. According to her parents, Kitty had always been afraid of water and had never learned to swim. Shortly after Kitty drowned, her father walked out on the family and was never seen again.

Fast forward twenty-three years to the day Emer saw a woman on the London Underground that looked like her dead sister. The woman couldn’t be Kitty because she had a different name, and a different family. But she also had a photo of Kitty and Emer as young girls in the collage upstairs in her house.

At some point after Emer had seen Annie on the train that day, someone pretending to be Emer had contacted Dee, asking her to find out if there was any possibility that Annie Holden could be Kitty Doran.

Those were the facts. Alongside them, Dee had noted down her list of questions:

What happened to Lucy Ryan?

Why was Kitty’s body never found?

Why did Eamon Doran abandon his wife and remaining child, and where did he go?

Did Annie actually have a photo of Kitty or Emer? Or had Dee made a mistake?

If it wasn’t a mistake, did that prove that Annie was Kitty?