Mary visited the valley for the last time on a cold, clear day in March. She didn't tell anyone where she was going; what would be the point? Helen might have understood, but she was still too angry with her mother to even have a civil conversation with her. Her younger sister - serious, unsentimental, ever-practical Jane - might pretend to understand, but she had never been very good at pretending. No, it was really much better that her daughters didn't know where she was going; they'd only worry. And nobody else would even care what a mad old woman was doing, climbing a mountain by herself.

It was perfectly possible to take a longer, easier route, of course, to walk around the mountain to the head of the valley and then follow the river up. She would never have considered going that way, though, even before they built the road that now made it easier than ever. Her husband always told her that there was only one way to approach the hidden valley, and that was the hard way. She wouldn't dream of contradicting him.

She'd started the long struggle up the grassy hill-side in the half-light before dawn. By the time she'd reached the foot of the rocky ridge and started to climb in earnest, the sun was just starting to dry the abundant dew that covered her eminently sensible walking shoes. At first, breathing hard and wincing at every step, the unaccustomed exercise had made her feel older than ever, but after a while her joints and lungs seemed to abandon their angry protests and settled into a sullen silence. She really started to enjoy herself then, falling into a relaxed and familiar stride that made her feel glad to be alive. Even as the sharp pain in her knees subsided, however, the dull ache in her chest grew ever stronger.

Looking down upon the valley from above, she had been disappointed. Through the early morning haze it looked grey and lifeless, the merest shadow of the magical place that lived in her memories. Had she really dragged herself out of a warm bed and trudged all that way for this? Starting down the slope, she determinedly pushed aside her disappointment and concentrated instead on where she was placing her feet. Only when the punishing incline at last began to level off did she trust herself to look up, finding herself, with a suddenly racing heart, in a completely different valley. Stripped of the mist's obscuring veil, with only few stubborn wisps still remaining, it had been transformed.

A vivid and familiar palette of colours clamoured for her attention. Here a thicket of spiky red and black branches was sprouting its first leaves: some pale and only just starting to emerge; others completely unfurled, but still limp and with an almost unearthly shade of green; a few already growing darker, their upturned surfaces firm and glossy. Then there were the marsh grasses, seemingly dull at first glance, until the wary eye caught the red and purple tones at the tips of their grey-green blades. Up on the slopes, last year's bracken was a riot of pink- or orange-brown, contrasting sharply with the lush grass that bordered it. And finally, lining the ridge and glistening in the jumbled beds of the streams below, the characteristic pink, grey and white stones, which she had always thought of as the bones of the mountain.

The spring sunshine dimmed and then brightened again, smugly claiming the credit for this colourful transformation, but its feeble attempts to warm her skin and dry her dew-soaked trousers still lacked conviction. She moved more slowly now, drinking it all in. The ache in her chest was threatening to overwhelm her, her nose prickling and her eyes brimming with tears.

In her mind's eye she saw him walking in front of her, smiling, beckoning, urging her on. Michael. Dear Michael. This had been their place, just as it had once been his; a little haven of happiness, far away from the world of care and woe. How many plans had they made here, how many mad and wonderful ideas had they concocted together? He'd proposed to her over there, kneeling on the wet grass and holding her hands tightly, like a desperate man clutching at a life-line. There, beneath that tree, they'd lain together for a long, glorious afternoon - the same afternoon, he had always insisted, that their first daughter had been conceived. So many happy memories...

Some sad ones too, though. Here was the crumbling wall that he'd sat upon, white-faced and fighting for breath, on their last trip here together. She had been almost as angry as she was scared, furious with him for hiding how much the once-trivial effort of coming here had cost him. She'd told him beforehand that it was stupid, joking that the climb alone "at your age" would probably be enough to finish him. "Better to finish like that," he'd told her seriously. "Than to die without even trying." She realised then, with a shock, that he'd already resigned himself to the imminent certainty of his own death. How typical of the man - that impossible, wonderful, beautiful man - that he hadn't been able to tell his own wife until that moment.

Afterwards, it had become her place. At first, she came to wallow in her grief, which she'd successfully hidden from the rest of the world, but which was by then threatening to eat her alive. Far from being consumed by it, she'd found an unexpected peace here instead, amongst the ghosts of happier memories. She brought the girls once or twice, but mostly she came by herself, simply to remember him, drawing strength from her memories and letting the valley soothe away all of her hurts. This place had become an enduring symbol of the life that they had shared together and a tranquil retreat from the frantic world. It was a comfort to know that it would always be there for her.

Or so it had seemed.

Now, at last, Mary allowed herself to lift her eyes and look to the near horizon, to the great angular edifice that had been erected at the far end of the valley. Already she could see the new body of water creeping up from the foot of the dam; she fancied she could see it growing, even as she watched. How long before it swallowed up all of this valley and with it her precious memories? Not nearly long enough for her to return again, she thought. If she ever did come back now, it would not be to a place that she recognised. No, this was her last chance to say goodbye.

The journey back was longer and harder. Grateful now for the walking poles that she'd brought with her, she crept painfully up the steep slope, stopping every few minutes to catch her breath and to wait for her head to stop spinning. I wonder what would happen if I fell now, she found herself thinking. How long before anyone noticed that I was missing? For a morbid instant, she imagined rolling down the hill and lying there, waiting patiently until the waters rose up and swallowed her. Then she shook her head, set her jaw and began to climb again.

She lingered at the crest of the ridge, staring down at the peaceful and still-unsuspecting valley, striving in vain to commit every last detail to memory. Finally, when the light began to fail and the temperature began to drop, she shut her eyes tightly and scrutinised the image in her memory. It would fade, no doubt, as all things fade, but she was confident now that its legacy would endure. Opening her eyes again for one last look, she wiped ineffectually at the tears on her cheeks and managed to smile.

Goodbye little valley, she thought, and then she turned away.