The wardrobe door was already ajar, so all he had to do was push the clothes to one side and step inside. Then he pulled the door shut behind him until its three magnets connected with a click. With his right hand, he fumbled along the back of the wardrobe until he found the hole, which was only just big enough for him to stick his middle finger in and reach the rectangular metal plate on the back, just above the hole. He pushed the plate to one side.

The lock mechanism clicked and the back of the wardrobe sprang open. He continued into the dark, closed the back behind him and pushed the metal plate back into its holder. Not just the middle one he had just opened, but the top and bottom ones that could only be accessed from this side. Finally, he reached up for the blackout blind, pulled it down to cover the locked door and turned on the overhead light.

The windowless room he was now in didn’t officially exist. Not even his landlord would find it, if he ever decided to pay a visit. The flat was still a one-bed, like his contract stated, just a slightly smaller one. And so long as no one was specifically looking for the missing square feet, they would never be noticed.

The extra wall dividing the bedroom down the middle had only taken a weekend to build, though he had both insulated it and used double plasterboards on each side. Even so, it had taken him more than three weeks to completely finish the project.

He’d had to put up new wallpaper, and to make sure it didn’t look too new and modern, he’d chosen a greyish-blue kind typical of the 1960s. The light from inside had also stubbornly kept leaking out along the edges of the newly built wall, but that had only taken him three and a half days to fix.

The secret room was almost a hundred square feet and furnished with a narrow bed, a work table with an internet-connected laptop and a desk chair. A built-in bookshelf covered the entire back wall, except for where the bed stood. Most of the shelves were still empty. Unlike the chest of drawers, which was filled with clothes and did double duty as a bedside table. Next to the chest of drawers was his store of tinned ravioli and drinking water, which, according to his calculations, should last him two weeks if he had to go underground.

One of his biggest challenges had been to figure out how to avoid a sanitary disaster when answering the call of nature. To take care of his urine, he had purchased ten one-and-a-half-litre, sealable plastic bottles.