Once Wallace got this far, he knew that, without access to the various codes and keys contained in those printouts, he couldn’t get hold of the kind of information he was hoping to find. It niggled and worried at him for weeks afterwards, until eventually he wound up blabbing his frustration to Casey while they were fishing and drinking down by the harbour.

This was when Wallace learned that Casey had a secret of his own. He was covertly working for the Patriots, just like I’m now secretly working for Mort Bramnik.

Casey explained that just a few months before, Greenbrooke had approached him about carrying out some kind of work for the Patriots. Greenbrooke tried to get Casey on side by saying how much Casey’s outlook and philosophy reflected his own. You know how Casey’s a big fan of Ayn Rand? Well, Greenbrooke apparently presented Casey with – get this – a signed copy of Atlas Shrugged, from the Authority’s own alternate. In return for working clandestinely for the Patriots, Greenbrooke told Casey, he would be handsomely rewarded. Not only with early retirement to the alternate of his choosing, but also with enough material wealth sourced from other extinct alternates to set him up for life, wherever he wound up.

Casey bit. The nature of all this clandestine activity? Nothing less than sabotage. Greenbrooke explained he wanted to hurt both Bramnik and his civilian administration, which Casey himself, after all, had never been afraid to criticize at length. If enough things went wrong, Greenbrooke suggested, the Patriots would be able to make a case for taking over operations on the island. In order for Casey to carry out his work, they would provide him with a portable transfer stage that he could use to make his own trips – but with a limited set of coordinates.

In one respect, I think Greenbrooke judged Casey correctly; they shared the same love for tradition, for the military, for rugged individualism.

But in other respects, Greenbrooke got Casey all wrong. Greenbrooke forgot that a man like Casey never likes having to kowtow to anyone else, whatever their similarities otherwise. More than that, Wallace explained to me, Casey smelled a rat. He figured that, instead of letting him retire, Greenbrooke was more likely to order his men to put a bullet in the back of Casey’s head and dump his body in the sea. That’s what Casey would have done had the roles been reversed.

Your next question might be, Why did Casey tell all of this to Wallace?