In September 2006, two groups of people crossed paths in the snow-capped Himalayas - one seeking freedom, the other adventure. A brutal shooting threw them together, changing their lives for ever.
Each year an estimated 2,500 Tibetans make the dangerous and illegal crossing through the Himalayas into India.
Many are young teenagers seeking freedom both in religious practice and in their education. A big incentive is the prospect of meeting their spiritual leader, the Dalai Lama, who lives in exile in India.
Murder in the Snow
Monday, 10 November, 2008
1900 GMT on BBC Two
In 2006 the plight of these refugees came to international attention when a group of mountain climbers witnessed and recorded Chinese border police opening fire on one group of pilgrims as they made their way across the Nangpa pass in the Himalayas, 18,000 feet (5,500m) above sea level.
Among this group were two teenage girls from Tibetan farms, 16-year-old Dolma Palki, and Kelsang Namtso, a 17-year-old nun.
Dolma is now studying at the Suja school in Dharamsala
They had been best friends since the age of 10 and together they hatched a plan to escape from Tibet and make the pilgrimage to India to see the Dalai Lama and to study.
"Three of us girls made the decision together. Escaping Tibet was always on our minds. Whenever I saw photos of His Holiness, I wanted to see him in person," recalls Dolma.
"One day Kelsang Namtso and I were in the field. She called me over and said: 'People are going to India. Do you want to go?'"
Some nuns had just returned to their district from a nunnery in India. The stories of their journey and studies there reassured Kelsang's parents and they agreed to let her travel to India.
Many young Tibetans risk their lives each year to illegally cross the border but Dolma's parents thought she was crazy to consider it.
They sought counsel from the local Abbott, who reassured them all that it was a good time to leave.
After an emotional and clandestine farewell, Dolma, Kelsang and their friends travelled to Lhasa to meet with a guide.
They handed over about £500 ($800) and were told they would be travelling with a small group for about four days, including perhaps a half day walk. They did not realise that the guide was lying to them.
Joining the group in Lhasa was 14-year-old Jamyang Samten, who had wanted to get out of Tibet since he was 10.
Jamyang attended a Chinese-run boarding school for nomadic children but was expelled at the age of 11 for misbehaving. After working for four years, Jamyang had saved enough money to escape.
The teenagers were packed into a truck with around 70 other refugees. Dodging Chinese patrols, the truck travelled only after dark.
The shooting was documented by a group of mountain climbers
On the third night it stopped more that 100km short of the border. For the next 10 days, the group walked through rugged terrain at night, sleeping rough by day. They had little food or water.
On the morning of 30 September, with the Nangpa Pass just ahead, the refugees heard loud bangs.
"We didn't know they were gun shots. We thought it was mountaineers setting off fire crackers for fun," Dolma says.
Meanwhile at the advanced base camp on Mount Cho Oyu, a group of mountain climbers were observing the scene. Many picked up their cameras and began videotaping and photographing the unfolding events.
Chaos ensued as it dawned on the refugees that the Chinese Border Police were shooting directly at them.
Dolma was just ahead of her friend, "I got really scared. I patted Kelsang on the back, 'Please go faster. We are in big trouble. The Chinese are chasing after us.'"
When Kelsang was shot Dolma says she felt as if her own body had been electrocuted. She wanted to go back and help her. But others in the group dragged her away, urging her to think of her own life.
Jamyang, who had splintered off into another group, was captured along with 30 other refugees and arrested by the Chinese Border Police.
He says he was beaten, interrogated and tortured with whips and electric cattle prods for three days. After three months in a Shigatse jail, his uncle paid a hefty fine and Jamyang was set free.
Everyone knew it was a dangerous journey, but no one imagined it would end like this.
Jamyang Samten and Dolma Palki talk about why they wanted to leave Tibet
Kelsang was shot in the back less than 400m from the Nepalese border and freedom.
At the time China's state run Xinhua news agency said that the Tibetans had refused orders to turn back, and that they had then attacked the People's Armed Police.
According to Xinhua, the soldiers were "forced to defend themselves."
Chinese Foreign Ministry spokesman Liu Jianchao told a press conference that "it is the responsibility of the Chinese border police to maintain peace and security."
Jamyang later made a second attempt to leave Tibet by a different route. This time he was successful.
He now goes to school in India with Dolma and other refugees who made it out of Tibet. Jamyang hopes to qualify as a teacher and work for the Tibetan community in exile.
Like all refugees Dolma and Jamyang got the opportunity to meet the Dalai Lama. He advised Dolma "that Kelsang died for a good cause and that her next rebirth will be a special one."
She says his advice has given her tremendous strength in continuing her education and following her dream to become a nun, in memory of Kelsang.
This World: Murder in the Snow will be broadcast on Monday 10 November at 1900 GMT on BBC Two. The programme is made by 360 Degree Films.