Sibilant hissing drew in to Cowl, from the shadows amid the machines, and expressed from that entity in words: ‘I do not give orders twice.’

Catching the attention of her companions, Makali twitched her head towards the exit, and the five of them began backing out of the sphere. Makali followed them, pausing at the exit.

‘The torbeast?’ she asked, knowing she was now risking her life.

Cowl hissed again as his face covering began to open up.

Makali fled.

If asked who she trusted, Polly could only suggest Nandru with certainty, since his fortunes were now utterly tied to her own; and Ygrol, maybe, because he was utterly ingenuous. The word ‘trust’ did not apply to Tacitus because, though always honest and utterly straight with the others, he also coldly informed them that he was loyal unto death to Aconite, and cared not one whit if the rest of them lived or died. Cheng-yi she felt was the kind of dog you daren’t turn your back on, and Lostboy she included in her general assessment of Aconite, for most of what rested inside his skull the troll woman had put there. The heliothant herself Polly considered too complex a being to either trust or distrust. Tack she trusted even less than the Chinaman, and when she spotted her erstwhile killer sneaking out into the damp night, she took up her taser, and the Heliothane handgun Aconite had provided for her, and followed him.

Rain was now steadily pouring from a dark sky, but it was a warm downpour and Polly relished it as she fixed her mask across and tied her hair back.

Now then, is there something Mr U-gov arsehole has neglected to tell us?

‘Well, I don’t think he’s out here to smell the roses, Nandru,’ Polly replied.

I wonder what it’s to be: some sort of double cross, or is he still going after Cowl?

‘We’ll find out soon enough.’ Polly set off after the half-seen figure. The light robe Aconite had provided him with was much more easily visible than the black skin-tight clothing Polly herself wore, but nevertheless she found what concealment she could. However, Tack did not look round once as he plodded stolidly into the night.

Polly tracked him down the hill, then up one bank of the river. She ducked down behind a low boulder when at one point he halted, turning his masked face up into the rain. She noticed that his fists were clenched at his sides, then she watched him bow his head and bring the fists up and crush them against his temples. Still he did not turn round, but after a moment moved on.

Migraine? Nandru suggested.

Polly did not answer, for just then Tack abruptly turned aside and she lost sight of him. Hurrying up to the point she had last seen him, she spotted a narrow watercourse leading away from the river bed, cut down through stone. Following this, she kept catching glimpses of him ahead of her. For a second time he disappeared, but then a dim light ignited somewhere in the watercourse, and she finally came upon a tent lit up from the inside.

Perhaps he don’t like company.

Much as she appreciated how much Nandru had helped her, she sometimes wished she had an antidote for his verbal diarrhoea. She studied the tent for long-drawn-out minutes, but no movement was apparent inside it. As she considered turning round and heading home, there came a muttered curse from the interior. Leading with the barrel of her handgun, Polly ducked down and pressed through the entrance.

Tack was sitting cross-legged at the rear of the tent behind a suspended chemical light. To his left lay an empty pack and on the ground to his right, rested a Heliothane carbine. He made no move for the weapon as she entered. When Polly moved to where she could more clearly see his face, she saw that his mask was off revealing a cold, blank expression. She removed her own mask to sample the air, and saw, down in one corner of the tent, some insectile oxygenating device.

‘I’m sorry I tried to kill you,’ Tack said emotionlessly.

He’s sorry. Well, that cuts no mustard on my fucking beef.

‘Go away, Nandru.’

Well, excuse me.

Polly felt the presence of Nandru fade as he took the other option now available to him: shirting his awareness into Wasp.

‘Are you really?’ she sneered at Tack.

He looked confused for a moment, pressed the palm of his hand against his forehead, then went on, ‘I killed Minister LaFrange, Joyce and Jack Tennyson, Theobald Rice and Smythe. I cut off Lucian’s fingers one by one until he told me the file-access code at Green Engine, and then I gutted the guard who tried to stop me breaking in there.’ Then he looked up, staring past her as if at something beyond the wall of the tent and beyond this time. ‘The bomb in the protest meeting against U-gov killed forty-eight people and maimed twelve.’

He fell silent, and she knew he was enumerating further killings and tortures in his mind.

‘Why did you come out here?’ she asked, uncomfortable with the ensuing silence.

His gaze tracked across to her. ‘I needed to think.’

‘Nice thoughts you have,’ she observed.

He flinched. ‘How could they be otherwise? I’ve led such a nice life.’

‘But it wasn’t exactly your fault,’ Polly conceded.

His stare was blank. ‘Yes, I accept that I had only as much control over my actions, before the moment Cowl took my mind apart, as any other machine. But that doesn’t help. It was me who planted that bomb. It was me who raped the teenage daughter of a certain terrorist, to force him to come after me. It was me who led him into a trap and blew his kneecaps away, me who worked him over with scopolamine, a scalpel and pliers, until I had extracted the required information. And it was me who then tied a kerbstone to him and dumped him off the New Thames Barrier.’

‘Did he deserve it?’

‘She didn’t.’

Polly was at a loss. She had followed him here expecting the man to be involved in something nefarious—and perhaps to have the satisfaction of putting a cluster of explosive bullets in his back in repayment for past intended hurts. But this was something else, though what she did not yet know. Maybe he truly felt remorse, or maybe that was just what he wanted her to think.

‘So you have suddenly become such a moral human being?’ she queried.

Tack snorted. ‘It’s not morality—it’s empathy. I cringe when I remember the things I did. I can still hear the sound of the wirecutters going through Lucian’s fingers and the sounds he made. I can remember the girl’s fear, then disbelief, then pain, every word she said to me while she begged for mercy, and I can see how I destroyed something essential.’

Polly sat back and crossed her legs, wondering at her own reaction. She had never killed anyone, but she had caused pain because of her lack of empathy. As for morality, previously she had never known the meaning of the word.

‘Aconite told me that’s the true mark of a criminal,’ she murmured.

‘Cruelty?’ Tack asked.

‘No, lack of empathy. The true criminal cannot conceptualize the experiences of his victims. He cannot feel their pain, or in any way understand their trauma. The true criminal is not a social creature. We were discussing her brother at the time.’

Tack shook his head. ‘In U-gov terms, I was not a criminal. I was merely their agent—the ungloved hand of their justice.’

‘They were the criminals,’ said Polly. ‘What they did to you was in many ways as bad as the things you inflicted on others. They suppressed your humanity and made you their absolute slave.’

‘Knowing who to blame doesn’t make me feel any better. There’s a grey area… Why didn’t I kill that terrorist cleanly rather than let him drown?’

‘Perhaps you felt his actions justified that punishment?’

‘Perhaps.’