As Vicky Jack sits in her Perthshire home looking out at Ben Sidhein, it is hard to believe this softly-spoken lady was the first Scotswoman to complete the seven summits challenge.

As Vicky Jack sits in her Perthshire home looking out at Ben Sidhein, it is hard to believe this softly-spoken lady was the first Scotswoman to complete the seven summits challenge.

When, aged 51, she finally climbed Mount Everest, Jack had achieved the remarkable feat of climbing the highest peaks in all seven continents.

Now an authorised biography of her life is being published, detailing just how her mission stretched her physical and mental stamina. In it, she tells how in her first Everest attempt she was lost without oxygen or her sherpa guide.

And she admits she has felt different since her second, successful, Everest attempt although she can't quite put it into words.

"I wouldn't say it was religious and I wouldn't say it wasn't religious," she said. "I honestly don't know what to call it. But I feel complete. It's a funny thing to say because I still get anxious about things in life now. I still want to go and see what's round the next corner, but I feel comfortable and complete within myself."

It was on Everest that Jack came closest to losing her life. The year of her first attempt marked the 50th anniversary of Sir Edmund Hillary and Tenzing Norgay's successful summit bid and the mountain was a magnet.

When the weather finally cleared and Jack could try for the top many others were doing the same. She found herself queueing at what is known as the Hillary Step, all the time losing energy in the thin oxygen.

Already exhausted she knew it was mad to continue and signalled to her sherpa guide that they would turn back. But as they began to descend she made the alarming discovery that both she and her sherpa were out of oxygen.

With their stark situation hitting home at 28,000ft, Jack's sherpa said: "I die. You die. We both die. I go" and disappeared down the ridge.

The rest of her descent is hazy in the memory. She staggered down the ropes, the dangers barely registering in her mind. At one point she stopped and asked two Japanese climbers progressing in the opposite direction for water.

They refused, and she became very angry not only at the lack of assistance but at her observation the pair were ascending Everest far too late in the day for a safe return.

Only later did she realise that she was the one moving in the wrong direction. In fact, she wonders if the Japanese climbers were there at all. She fears they were merely hallucinations, created by her oxygen starved brain.

Jack did make it back to base camp, but she was so exhausted she had to be flown off the mountain.

Yet she's extraordinarily generous about the deserting sherpa. She said: "He was a young lad. He wasn't wildly experienced. He thought he was going to die. If you suddenly discover that you are going to die and you have not been in that position before, you cannot predict how you are going to react."

All this might imply Earth's highest mountain grabbed Jack's attention in childhood, but that is not the case. The biography, by Anna Magnusson, shows her ambition arose from a series of smaller, more attainable goals.

"I maybe did three or four Munros as a child with dad and the family and then nothing until my 30s," she said.

It was then, planning to entertain English friends, that she realised she didn't know Scotland and decided climbing all 277 Munros was the way to rectify this.

But the moment she bagged the last 3000-footer was tinged with an uneasiness: What, she wondered, could she do next?

Eventually someone suggested she attempt the highest mountain in Europe and she began preparing to scale not Mont Blanc, but Mount Elbrus, just north of the main Caucasus range in Russia.

She said: "I had this mental picture that the rest of the group would all be men, hardened men, who were very strong and probably technical climbers. I was just a hill walker. I mentally put them on to a different level."

In the end she emerged as one of the fittest in the walking party and within weeks of returning to Scotland she had set herself the challenge that brings us here today.

Jack knocked off Kilamanjaro in Tanzania, Aconcagua in South America and the Vinson Massif in Antarctica, at an amazing rate.

The person who shared the detail of her mountain climbing trips was Maureen Jack, her mother.

When in January 2000, with very little warning, her mother died, Jack - never one for hyperbole - says her heart was broken. At the same time she was working long hours amid difficult changes at North of Scotland Water and preparing to climb Mount McKinley in Alaska.

Jack said: "The hardest training was for McKinley and I was mentally in the worst place and pressurised at work."

Some 15000ft above sea level, leaning into a wall of ice, Jack's resilience finally broke. The leader of her walking party was telling her to get her act together when the tears came. She stopped and sobbed.

Although she still made it to the top of McKinley, she did not enjoy the climb and felt unwelcome on the summit. It is not the only unhappy moment in Jack's biography, but it's moving for anyone whose shell has given in at the worst moment.

The happy ending of course is that Jack did summit Everest in 2004, in comparison an exceptionally smooth experience.

The question of what to do next does not appear to trouble her. "Something will arrive," she said. "How, where and why I've no idea, but I know it will arrive and it's just exciting not knowing."

The Sky's the Limit by Anna Magnusson, published by Black and White, is available in hardback priced £17.99