“‘Light duties,’ the Brigadier had called it, and then later, registering Mike’s dismay, he’d amended that to, ‘Vital intelligence work. I need someone I can trust, Yates,’ he’d said, ‘someone with integrity. Someone with a clear head, who can sort out the wheat from the chaff.’
A clear head. That was a joke for a start. It was precisely because of his inadequacy in that department that Mike had been given this assignment. He couldn’t believe that almost six months had passed since it had all begun. It seemed like no time at all since he had been sitting behind the desk at Global Chemicals in Llanfairfach, purporting to be the ‘Man from the Ministry’. As usual things had gone a bit haywire before the Doctor had managed to sort it all out. Turned out the company, which had been pumping lethal industrial sludge into the village’s abandoned mine workings, was begin run by some sort of super computer which called itself BOSS and which could scramble its employees’ brains, turning them into mindless zombies.
For a while Mike himself had fallen under its influence. BOSS had dismantled his thoughts and put them back together in a different order, had made him believe his friends were his enemies. He’d nearly shot dead the two people he trusted most in the world: it had seemed perfect sense at the time, before the Doctor had shown him the error of his ways with the aid of a blue crystal he’d picked up on some far-flung planet or other.
After that, Mike had been fine for a while, had felt better than he’d felt for a long time in fact. But then weird thoughts and feelings had started to spring up, like weeds in a well-ordered garden. He had begun to suffer odd bouts of depression, feelings of futility. Despite the vital part he’d played in repelling the many and various threats to the Earth over the years, he had started to convince himself that his life was meaningless.”
~Deep Blue by Mark Morris