‘You can come upstairs, you know. We don’t bite,’ said Henley.
She watched Ezra rip the brown tape of a cardboard box.
‘I’m still emotionally scarred,’ he said, before registering Henley’s stricken face. ‘Oh, shit. Sorry. I didn’t click. It’s just a pair of trainers.’
‘It’s fine.’ Henley felt her shoulders drop a little, as she looked at the pair of black trainers Ezra was holding up.
‘These are a pair of classic Air Jordans straight from the States. You can’t get them anywhere in the UK. So, you got the map that I left on your desk. I know that you like things ol’ skool.’
‘Says the man who just spent a small fortune on a pair of vintage Air Jordans that I owned when I was fourteen.’
‘Actually, my uncle sent them to me from New York. Early birthday present.’
‘You’re something else. So, this cell site map?’
‘Yep, for Kennedy’s phone. The one that you haven’t found yet. Here let me make some room.’ Ezra picked up his laptop, placed it on the windowsill and cleared the desk of his keyboard, Xbox controller and his new trainers. ‘As you know, Kennedy’s phone was alive and kicking until last Tuesday and his tag went dead in Ladywell Fields on the previous Friday. So, I’ve focused on that time period, between Friday night and Tuesday morning.’
‘Did Pellacia ask you to do this?’ Henley couldn’t hide the fact that she was impressed.
‘Nah, I thought that it would give me something to do and, to be honest, I’m nosy. Right, you know how mobile phones work.’
‘Ezra! Of course I know.’
‘Just checking. So, mobile phones connect to the nearest cell site mast when you turn them on. Now Kennedy’s phone is a bit basic and has no location tracking, but his phone still connects to a cell site mast, and the ones in London have a range of a little over half a mile.’
‘The blue dot here.’ Henley pointed to a blue dot in the middle of Ladywell Fields. ‘That’s Kennedy’s phone?’
‘Yeah, and it connects to the cell site mast on top of Lewisham Hospital and then it starts to travel. Remember, this isn’t the exact location—’
‘But it’s within a mile of where Kennedy is?’
‘Exactly, so follow the blue dots.’
Henley traced her finger along the map, thorough Lewisham, Brockley, Nunhead and Peckham. Her finger stopped on the last blue dot. A cell site mast on top of the Peabody Estate in Camberwell, across the road from the Magistrates’ Court.
‘Whoever took Kennedy and Zoe avoided the main roads,’ said Henley. ‘This is to scale, isn’t it?’
‘Yeah, 2 cm is a mile, and a mile isn’t hitting Lewisham High Street, Lewisham Way or New Cross Road. All of these masts are on the roofs of blocks of flats in the back streets.’
‘What’s this green dot?’
‘That’s Zoe’s phone and it follows the same route. Sometimes, her phone connects to a different cell site mast, like here.’ Ezra pointed to a green dot on a road next to Morrison’s supermarket in Peckham. ‘She’s on a different network, so that would make sense.’
‘That’s further evidence that Zoe was with Kennedy.’
‘Except her phone stops connecting to any masts after the Morrison’s; which means that her battery must have died.’
‘But Kennedy’s phone carries on into Camberwell?’
‘And then it bounces off three masts in the area.’
‘Why would it do that?’
‘Most likely the signal is weak and it’s trying to connect to the nearest mast,’ Ezra explained. ‘These three dots here are the last three masts that Kennedy’s phone connects to on Tuesday morning.’
Henley peered down at the map. The red dots were on top of Picton Street, not too far from the court. Another was on top of the Camberwell College of Arts and the last dot was on Wilson Road.
‘You know how triangulation works, don’t you?’ Ezra stared at Henley quizzically.
Henley thought back to the boring cell site analysis lecture that she, Stanford and Pellacia had been sent to almost nine years ago. They had sneaked out halfway through and headed to the pub.
‘If a phone is picked up by three cell site masts, you can calculate the distance to the phone from each point.’
‘You get a B for effort.’ Ezra picked up a black Sharpie from his desk and drew a circle, 2 cm in diameter, around each red dot. ‘You see this area where all three circles overlap? Kennedy’s phone is somewhere in that area.’
Henley traced her finger across the small oval area on the map. Gables Close, Hanover Street, Peckham Road and Stanswood Gardens. An area populated by blocks of flats, council offices, doctors’ surgeries, long roads of Victorian terraces and building sites. Somewhere in that space of just over half a mile was where Sean Delaney, Daniel Kennedy and Zoe Darego had been murdered.