Detective Constable Carl Hoskins smiled to himself as he opened the first file of CCTV footage. Cell site analysis put Beatrice Ulbricht at Clandon railway station at a quarter to four on the Tuesday afternoon. That would be exactly right to catch the South Western Railway 15.48 service to Waterloo. There were two CCTV cameras car park side at Clandon, covering the station apron and the ticket machine. Right on cue, Ms Ulbricht appeared at 15.45, right below the left-hand camera, hurrying through the rain and dodging puddles. She was wearing the navy coat, mauve fedora and scarf, and carrying a violin. There were no platform cameras, so it took a while for Hoskins to establish which carriage she had boarded. Each coach had had one internal camera at each end. He had already been sent a link to the footage from the 15.48 which was stored on the South Western Railway database.

She had got on right at the back, carriage eight. She sat roughly in the middle, reading a magazine. There were a few other passengers, only one having got on with her at Clandon. After five dull minutes trying to ignore a businessman picking his nose right opposite the camera, Hoskins fast-forwarded right to the end, the final two minutes before arrival at Waterloo. By then the carriage was packed. Almost everybody had stood up and crowded the doorways for a fast escape upon arrival. He couldn’t see her, not even the hat. As the doors opened, the detective watched the raincoated commuters squeezing off, laden with briefcases, umbrellas and phones.

Once half of them were gone, Hoskins did a double take.

The woman had completely vanished.

He rewound three minutes and tried again. No sign of her. ‘Christ, I bet she’s moved to a different carriage,’ Carl muttered. He looked through the data files. Eight carriages, sixteen cameras. Assuming they all worked. There were often one or two out of action. He put his head in his hands. Gillard was not going to be happy with this. He’d lost her somewhere. But he knew from the cell site analysis that she had made it as far as Waterloo.

Thursday

The Brentford waste transfer station is an old landfill site in West London, squeezed between clusters of railway lines. High razor wire fences, a variety of elderly cranes, eight-wheel quarry lorries and lots and lots of noise. DCI Gillard and DC Carl Hoskins were given fluorescent red high-vis jackets on arrival, and shown the main activities of the site, which were not highly sophisticated. Essentially, tipper trucks dumped vast quantities of mixed waste on the concrete floor of the five-acre facility, and a variety of machines, including a crane with suspended magnet, went through it looking for recyclables. Forget plastic, glass, paper. The only stuff worth retrieving at this stage was ferrous metals, thanks to the magnet, and copper, much of which was retrieved by hand from cables, old televisions and so forth.

Manager Tony Lowgreave brought them into the office, the higher of two stacked Portakabins, reached by a rickety ladder. He offered them scalding hot instant coffee in flimsy plastic cups.