They slipped inside as the gate began to close, and stood in the dimly lit tunnel, waiting while the driver parked up and disappeared through a door at the rear of the building, apparently without noticing them.

Hawkins watched her go before turning to assess their surroundings. The low tunnel between the flats was unbroken by windows or doors, although White’s flat formed one side of the passage. Bare brickwork was thrown into relief by the dull glow of LED up-lighters, one mounted in each of the four corners. Hawkins couldn’t see any cameras here, thereby reducing the likelihood that she and Mike would soon be explaining themselves to any private security firms.

She walked to the end of the tunnel and paused to make an assessment of the car park. The compact area was surrounded on three sides by thick foliage, which ensured it wasn’t overlooked. It contained markings for six cars, three of which were empty; the others occupied by the recently deposited BMW, a sporty Mazda two-seater and a small Audi hatchback. Soft lights were on in two of the four flats, but it appeared that none of the residents had noticed their uninvited guests’ arrival as she rounded the corner to find two windows at ground level in the back wall, both firmly closed.

There were no lights on inside White’s flat, but at least there were no shades or drawn curtains to obscure their view. Hawkins selected the torch function on her phone and shone it in through the glass. A kitchen, modern in design, with empty surfaces.

No help.

‘Hey. Look at this.’

Hawkins looked up to find Mike already at the second window, also using his phone, waving her over. She joined him, adding her light to his.

For a moment, neither of them spoke.

Hawkins moved her torch slowly around the small space. Obviously, this back room had received little attention from White in the two months since his arrival. There was no furniture except a basic desk and chair right under the window, no curtains – just a blind that hadn’t been pulled – and no lampshade on the bare bulb hanging from the ceiling.

But there were books.

Cardboard boxes were scattered all over the floor, most of them large, with the logo of a removals company printed on the sides, others smaller, more like packages sent through the mail. And every one was spilling over with large hardcovers and smaller paperbacks, many left open, as if abandoned in the desperate pursuit of an idea.

Hawkins finished scanning the room and turned her light back to the table under the window, where more books lay ajar. Except here, the print on their pages was close enough to read.

‘What is this?’ Mike whispered.

Hawkins moved her beam over to join his, lighting images she wouldn’t have recognized a week ago.

But now they made complete, chilling sense.