Now, in response to the occasional drowning, the state had installed a wide-meshed steel grate to cover the pool and jumping in was no longer an option.

As the three conspirators got to the low wall, the woman – she was by all accounts the leader – looked back and made sure that their car had pulled out of its space and was now idling, ready to take them out of here. There was a young couple on the platform with them, the boy’s arm around his girl, both of them mesmerized by the rushing water, unlikely to move away in the next five minutes.

A solo man, mid-fifties, in shorts and hiking boots, was climbing the low steps to the temple even as she waited, and behind him a family of four were getting up from their blanket, looking like they were walking this way.

The shorts and boots man caught her eyes for an instant, and she too quickly – stupidly – looked away. Guilt, guilt, guilt. He kept looking at her. She’d caught his attention, a critical mistake. He seemed to notice the picnic basket on the ground at her feet. His brow darkened, perhaps at the basket’s unlikely presence there, perhaps at the somewhat odd trio in scarves and pulled-down hats, jackets, and heavy pants.

She cast another quick glance to the family behind them. Yes, they were coming here, too, up to the temple. Their car was in place now, waiting. She couldn’t wait any longer, even if it had to get a little ugly. They’d planned for this contingency. They were ready.

She nodded to her two partners, jerked her head indicating the middle-aged solo hiker. In their planning meetings, they had decided that if fate handed them a situation like this, they would take full advantage of it. This would increase the profile of what they were doing. The public outcry was always vastly more satisfying if people got hurt or dead. That possibility made the game that much more meaningful. It also gave it a greater edge of excitement.

One of her men lifted the picnic basket to the edge of the railing while the other strolled casually over behind the man, who was now – apparently – transfixed by the show beneath them, the crashing water and noise and simple power of the spectacle. But then he looked up again and saw the picnic basket in its even more unlikely place. He started to raise a hand, began to speak so she could hear. ‘Hey, what’s…?’

It was time to move. Another nod and both men went into action. Her partner, who had once jumped into this temple to prove his manhood, caught the solo hiker from behind and flipped him over the edge as if he were a sack of flour. At the same time, her other partner had opened the top of the basket and taken out one of the five-gallon buckets, dumping it whole on to the grate while she did the same with the other one.

And then they were running, the basket left behind, the teenage lovebirds left flat-footed, unable to decide whether to help the older hiker or chase the bad guys.

They skirted the approaching family on a dead run, piled into their waiting Camaro, and sped with squealing tires from the parking lot.

Hardy heard about it on the radio on the way to his office after his talk with Glitsky. The emergency news report was warning citizens of San Francisco to avoid using their tap water until the actual substance that had been dumped into Crystal Springs could be positively determined.

‘… although the labeling on the buckets recovered at the Pulgas Water Temple led authorities to suspect that it is the gasoline additive MTBE…’

Suddenly Hardy reached forward and turned up the volume. He’d never heard of the stuff before this week and now suddenly it was everywhere. The announcer was continuing. ‘A group identifying itself as the Clean Earth Alliance has faxed a communiqué to this station and other local news media claiming responsibility for the poisoning.

‘Damon Kerry, the candidate for governor who has been running on a platform to outlaw the use of MTBE as a gasoline additive in California, is in San Francisco today. In a just-concluded press conference at the St Francis Hotel, he responded to critics who have accused him of some kind of complicity in this attack. He had this to say about this latest escalation in what has been called the gasoline additive wars.’

Hardy had arrived at the entrance to the parking lot underneath his building, but he waited out in the street, not wanting to lose any of the transmission. An angry-sounding voice came over his speakers. ‘The people who have tried to poison San Francisco’s water supply are terrorists. They say that the purpose of this poisoning is to call the bluff of the oil companies who contend that MTBE is not a significant health hazard in drinking water. They say that this vile act will dramatize their position. But I say that what they have done is unconscionable and criminal. No one associated with my campaign has anything but contempt for these people and their actions.’

The emergency bulletin switched back to the station’s DJ, again cautioning citizens about the hazards of drinking the water, and giving some more details about the attack itself, the man who’d been pushed over into the temple and who was now in critical condition with a broken back, and the spotty descriptions of the terrorists.

Hardy heard it all in a kind of trance, then looked at his watch, slammed his car back into gear and pulled out on to Sutter Street. Whatever he’d been planning to do in his office could wait. He wasn’t a dozen blocks from the St Francis and that’s where he was going.

Al Valens was in charge in the lobby. He was short, energetic, well dressed and powerfully built. Hardy stood on the sidelines for a moment inside the revolving doors of the hotel’s famous clock lobby, taking the lay of the land.

Valens was smiling, frowning, slapping backs, nodding sagely – whatever the minute demanded. Reporters, the curious, and the usual press of clueless tourists were still milling about. Cameras and lighting equipment were being packed up and put away. ‘Hey,’ he heard the short man say to a small knot of reporters, ‘You heard Mr Kerry say it, and now you’re going to hear Al Valens say it. We had nothing to do with this. Nothing. This is awful. These people are cretins.’

Valens threw a worried glance up the stairs to the Compass Rose Bar. Hardy and Frannie had met there a hundred times. He knew where Kerry was hiding.

There was, of course, still some security around him – four uniformed hotel guards, a plain-clothed bodyguard, and a man in a tuxedo whom Hardy recognized as the room’s maitre d‘. Kerry himself was in an area cordoned off behind a velvet rope. He sat forward, alone, on a low couch. Occasionally, he would reach for the glass of water that rested next to an iced pitcher on the table in front of him.

The name and face of Damon Kerry had been familiar in San Francisco for the better part of the past twenty years. He’d made his debut as a city supervisor. There he served two fairly distinguished terms that gave the lie to the initial impression that he was a spoiled rich kid whose daddy had bought him the office as a toy. Kerry was always a Greenpeace, Save the Whales for Jesus kind of guy – in San Francisco that always flew politically – but he also actually put in time cleaning up oily bays and beaches, serving in soup kitchens, doing things.

When he moved up as an assemblyman in Sacramento, he continued with his activism – especially in environmental areas – and his San Francisco constituency never abandoned him. He was their boy, liberal to the bone, sincere and electable, but always before in a low-key way. He was about to be forced to leave office under California’s term limit laws, and this – some said more than any personal ambition for higher office – got him rolling on the MTBE bandwagon and into statewide exposure. Also, of course, Al Valens got involved.