O’Grady carried on running, galloping along the next passage. He didn’t think the car, or whatever it was, would be able to fit down this one, and risked another glance back. The single remaining light had stopped at the junction. As he saw this, the arched entry to another passage came up on his left. He slid to a halt, seeing thirty yards of black tunnel, and at the far end of that unrestricted streetlighting.

He hurried down there, now aware that he was an unsightly mess – sweaty and panicking, with a firearm in his hand. He could discard the gun, of course; just release it. It was no use now anyway. But his fingerprints were all over it. Suppose the police married that one with the gun that had been used to kill Frank McCracken and his girlfriend? Suppose it had been used to kill other people before O’Grady had come into possession of it?

He shoved it into his coat pocket as he staggered out onto the pavement of a main road, which he recognised as Bakerfield Lane. His normally impeccable hair was now a wringing mat, his breath coming in wrenching sobs. But the luck that had saved him from the ambush in the alley was still holding, because a couple of dozen yards to his left, a night bus, a double-decker, idled at one of its stops. Both sets of its doors, front and middle, stood open as it awaited last-minute customers. Walking quickly towards it, straightening his tie and the lapels of his coat, O’Grady climbed on board.

He was the only passenger downstairs, so he found himself a seat easily.

All this was good, in fact excellent – his pounding heartbeat began to slow – except that, no, on second thoughts it wasn’t good at all; the bus was well-lit and if someone came around the corner now, he’d easily be spotted.

O’Grady got up again, walked to the spiral staircase, and ascended to the top deck.

Up there, he wasn’t alone. There was someone seated at the very front. But that was okay. He went to the back and sat down. Someone had slashed the seating, so all the stuffing hung out, but he didn’t care. Again, that was normal. Everything had to be normal now … ordinary, innocuous. He placed the briefcase on his knee and waited, though fresh sweat seeped from his brow as he wondered how long it would be before the bus set off.

Glancing down through the grubby window, he saw a Bakerfield Lane now bare of traffic and pedestrians. He looked to the front again, feeling tense. They had to make a move soon. What was the point in sitting around? There was no one else here, no one was rushing to catch a bus at this ungodly hour.

With a jolt, the vehicle lurched from the kerb.