The useful tricks you could learn from a lifetime of dealing with terrorists, thugs and psychopaths. Ben couldn’t help but wonder how many of those would be waltzing unimpeded through the tunnel today, this week, this month, happily avoiding running the gauntlet of airport security. The disparity between the two forms of travel was plain crazy. You were forbidden to take a can of soup or a badminton racket onto a plane for fear that such items would imperil the lives of your fellow passengers; and yet there was little to prevent some enterprising jihadist suicide bomber or other nutcase from packing a car full of PETN high-explosive and letting off a nasty little surprise midway beneath the English Channel. It would almost certainly happen one day.

But it wasn’t Ben’s job to question policy, least of all if his situation could benefit from its slackness. After the security point he presented his fake passport to the British end of the customs check. Then he was being waved through and following the EMBARQUEMENT signs for boarding. A staff member in an orange high-vis jacket directed him onto the train, where vehicles lined up nose-to-tail like cattle being shipped to market. Ben killed his engine, rolled down his windows, and soon the train got rolling. As they hurtled along fifty metres below the sea bed, he sat quietly resisting the urge to smoke while looking once more at Saunders’ file on the target. The video clip of Grace and her intruders was just a tap of the screen away, but he couldn’t bring himself to look at it.

Thirty-five minutes later, at three a.m. local time, Ben rolled the Alpina off the train on the other side of the Channel, in the port town of Folkestone seventy miles from London. The address that Saunders had given him was in the heart of the city, on the cusp between Lambeth and Waterloo not far from the river. In some parallel fantasy universe, Ben might walk into Wolf’s apartment and find him sitting there unawares, sipping a cup of tea while idly planning his getaway sometime in the near future. In the real world, Wolf was somewhere on the far side of the planet and the spooks had already been through every square inch of his place any number of times, days before Saunders had resorted to his alternative plan of extorting Ben to pick up the cold trail.

Ben would soon find out. Somewhere near the rural Kent village of Charing he detoured into the countryside and found a deserted back lane where he could retrieve his pistol and ammunition from their hiding place. Then he was back on the road and speeding towards London with the loaded Browning nestling comfortably in its traditional place behind his right hip. By 4.30 a.m. he was parking the car close to Wolf’s address, ready for whatever he might find there.