Tess felt her suspicions dwindling. Despite her fear, Gerrard had begun to win her respect. 'He'd be making a mistake if he dumped you.'

'Write him a letter. Tell him so.' Gerrard chuckled. A few moments later, he sobered. 'Because you're an expert in these matters, maybe you know this story, but I'll tell it to you anyhow.'

He was interrupted. A voice asked, 'Sir, would you care for a drink?'

Gerrard glanced up. A flight attendant stood beside him. 'The usual. Orange juice.'

'Sounds good to me,' Tess said.

As the flight attendant departed, Gerrard said, There's a man I beard about who lives in Iowa. A farmer. His name's Ben Gould. He's a member of the National Audubon Society. He's also an amateur climatologist. Near his barn, he's got a shed with a rain-gauge, barometer, wind indicator, and various other weather-analysis instruments. Two summers ago, after an extended period of drought that just about killed his corn and soybeans, his farm was blessed with several days of heavy rain. Or at least Gould thought his farm had been blessed. He put on rubber boots and slogged through mud to his weather shack. His rain gauge was almost full. He poured its contents into a sterile container, carried the container into his shack, and dumped the liquid into an instrument that analyses the chemical contents of water. This instrument was computerized. Red numbers glowed on a console. Two point five.'

The flight attendant handed Tess and Gerrard glasses of orange juice along with napkins.

They nodded their thanks.

'Two point five,' Gerrard repeated. 'What those numbers represented was the pH of the rain, the level of acid. The rule is, the lower the number, the higher the acid. Pure rainwater registers at five point three. But two point five! Gould was shocked. He told himself that there had to be a mistake, so he doublechecked his readings, using rain from another gauge. But the instrument's console showed the same numbers. Two point five. That's the acidic level of vinegar. Gould suddenly realized why his crops looked stunted. Vinegar? That's what you put on a salad . Not on your crops. It could rain every week, and Gould's crops would still look stunted. In a panic, he examined his wind charts. Global warming and its erratic effects had caused the jet stream to veer unusually southward. Into New Mexico. Then across Iowa. New Mexico's copper smelters are notorious for spewing outrageous amounts of sulphur fumes into the atmosphere. Those sulphur fumes, as you know, produce acid rain. And acid rain, in never before such intense concentration, was poisoning Gould's land.'

Pausing, Gerrard sipped his orange juice. 'Anyway, that's my story about vinegar. I wish I could say it had a climax, a happy ending, but the fact is, Gould's crops are still being poisoned, and there won't be a happy ending until we have legislation that forces those copper smelters and other heavy industries to clean up their act. Not just legislation in America, but worldwide. In Germany and Czechoslovakia, for example, there are thousands of square kilometers of woodland that have been totally destroyed and blackened by acid rain.'

Tess nodded. 'I know about those sections of Germany and Czechoslovakia, but your story about Iowa is new to me.'

'Then write an article on it. Maybe it'll do some good, get people thinking, motivated enough to write to their congressional representative, demanding controls.'

'I will,' Tess said. 'Poisoned forests don't seem to bother people unless they see the devastation. But a personal story, like Gould's, might make the crisis vivid.'

'And while you're at it, write the other story I'm about to tell you, the one about the frogs.' Gerrard drained his glass of orange juice and set it down. The main character in this one is a biologist named Ralph McQueen. His specialty is amphibians, and each year he likes to make a field trip into the Sierra Nevadas. A decade ago, he checked thirty-eight lakes and found them teeming with yellow-legged frogs. Last summer when he went back, he couldn't believe what he found or rather didn't find. The frogs had vanished from all but one of those lakes. In shock, he tried to discover why they'd vanished. His best guess was that some kind of deadly virus had wiped out almost the entire local population. But when he went to a herpetology convention in Brussels last fall, his shock became greater. It turns out that the Sierra Nevadas aren't the only area where frogs are disappearing. From colleagues, he learned that the same thing was happening all over the United States and indeed all over the world – in Costa Rica, Japan, Europe, Australia, Africa, Indonesia, Malaysia, South America, everywhere. The frogs are dying, and no one's quite sure why. Acid rain, pesticides, water pollution, air pollution, global warming, too many ultraviolet rays caused by the hole in the ozone layer. Maybe all of those. It's hard to say. But the interesting thing about frogs is that they don't have scales to protect them, and they breathe through their skin, which is very sensitive. That makes them extremely vulnerable to damaging changes in the environment. It used to be that coal miners took a caged canary into the shaft they were working on. If odorless poisonous gases built up, they'd know because the canary, so small, would die first. The miners would have a chance to run from the shaft.'

Gerrard furrowed his brow. 'Possibly the frogs are canaries for the planet. Their massive extinction might be a warning that something's very wrong. What's more, their extinction could have disastrous effects on the world's ecology. The frogs eat huge amounts of insects. Without them, flies and mosquitoes – to name just a few – will breed out of control. At the same time, larger life forms such as birds and animals depend on the frogs for food. Without the frogs, those other life forms will die.

'Frogs.' Gerrard shook his head. 'So seemingly trivial. So formerly common. So much a part of nature that we hardly noticed them. I suppose a lot of people could care less if they're dying, but what those people don't realize is that the frogs are an environmental cornerstone, and without them…' Gerrard's voice dropped, his tone despondent. 'Write it, Tess. An epitaph for the frogs, for the songs they no longer sing. A warning to everyone who still hasn't realized how endangered the world has become.'

'I will. I promise.'

Gerrard clasped her hand once more. 'I told you those stories not just because we share the same concerns or because the stories relate to your work. I had another motive, one that involves the heretics.'

Startled by the mention of the word, Tess came to greater attention.

'What I didn't indicate earlier,' Gerrard said, 'is that as much as we can determine, the heretics' conspiracy to terrorize corporations and infiltrate governments, to assassinate politicians and replace them with the heretics' own representatives, to blackmail other politicians in order to control their votes on environmental legislation, is due to the heretics' fear about the safety of the world. The photograph you showed me symbolizes their motive.' Gerrard gestured as if tracing an invisible image. 'A good god trying to fertilize the earth. An evil god trying to stop it. The heretics believe that the evil god has assumed control and is using every effort to destroy the planet.' Again Gerrard frowned. 'I'm sure you can understand the heretics' point of view. The evidence of the planet's destruction is all around us. Their intentions are the same as yours and mine, although their methods, of course, are repugnant. But a part of me, I confess, sympathizes. If a person gets frightened enough, if legitimate methods don't work, sometimes desperate measures are required. I don't approve, but I do identify with their desperation, the same desperation that forced me to vote against the president and for the Senate's clean-air bill. What I'm getting at is that good and evil aren't always as easily distinguishable as they might seem. If the heretics manage to save the planet, perhaps in the long run their methods are justified. I really don't know. I'm a politician, not an expert in ethics. But I'll tell you this. There are times when I hesitate, when I question how much force we should use to hunt them. If my children live to have grandchildren and those grandchildren breathe clean air, drink pure water, eat uncontaminated food, and flourish, maybe the heretics will have been right. I just don't know.'