‘Stop the car. Now.’
They were speeding down the Embankment, the river opening up like a black chasm on their right.
Caleb checked his rear-view mirror, then twisted the steering wheel and pulled the car into a side street, decelerating rapidly, bringing the car to a sudden stop.
Sara held up her hands.
‘OK, who are you?’
‘No friend of MI5, that’s for sure,’ said Caleb. ‘I know they’ve been chasing you. Since you were a child. My wife …’ A flicker of emotion overtook him, an infinitesimal hesitation, like a moment of vertigo, and he changed direction. ‘They think you attacked a military base. Killed everyone in it. They showed me a video of you as a child. I saw you weren’t capable of that. I wanted to get to you before they did.’
Sara held him in her gaze. Memories of her childhood were bleeding back, the blackouts, the school fights and the part of her that seemed to lurk in the shadows. His faith in her outweighed her own. Did she know what she was capable of? Attacking an army base sounded alien to her, as if Caleb was describing her sprouting wings and taking flight. But how much did she really know about herself?
‘And how do you know where my mother is?’
‘Your locket,’ said Caleb.
He switched on the overhead light, dousing the front seats with a faint glow.
Sara’s hand went instinctively to her necklace and gripped it protectively.
‘What about it?’ she said.
‘Can I see it? I will give it back. I promise.’
Sara weighed his words and then pulled the locket over her head and handed it to him.
Caleb took it, holding it with infinite care.
‘We need more light for this,’ he said, reaching into his pocket and pulling out a thin matchbook. He pulled out a match, striking it and holding the bottom of the locket up to the flame.
‘I saw the locket in the video. Look at this number.’
He tipped the side of the locket towards Sara.
515195140126923.
He handed the locket and the matchbook to Sara and pulled out his phone, opening an app and typing in the number.
‘I ran it through some software I designed. It hacks codes. Look.’
515195 14 01269 23.
515195 N 01269 W.
51.5195° N 0.1269° W.
‘A longitude and latitude, run together as one number,’ said Caleb. ‘Your mother used a key, replacing N with its numerical position in the alphabet, and did the same with W. The locket code was a set of coordinates.’
She reached out for the phone and took it from Caleb. Her chest was so tight she could hardly inhale. She typed the coordinates into the Google Map function.
The map plunged from its default aerial view of Europe across towards England, and then tilted down into London, causing districts to expand and separate again until the Bloomsbury area of the city filled the screen.
A red flag planted itself in a spot a hundred yards from the British Museum.
Sara pressed the Street View option. A photograph appeared of a three-storey Victorian building covered in dishevelled building works. It looked abandoned.
She stared at it, mesmerized.
What she had been carrying around with her all this time was a coded message from her mother.
The locket was a fail-safe: a map to somewhere with answers. Her mother had not abandoned her. She had left her a compass to find her way.