THE door bell rang on the morning of July 20, 1991. When Mrs Poon opened the door, she found a group of Customs and Excise Department officers anxious to get in. A warrant was produced and the mother, flustered and confused, dutifully let them search her home. By the end of the morning, she would discover her 18-year-old daughter, who was supposed to be camping in Lamma with friends, had been arrested in Singapore for drug smuggling. By the time the uniformed strangers had conducted their restrained but thorough search, the 55-year-old housewife's quiet existence had been shattered. Her daughter, Yuen-chung, a Christian, had been caught at Singapore's Changi Airport after flying in from Bangkok with a friend. Airport officials had found 6.52 kilograms of heroin in their luggage. There were so many questions. What was she doing in Singapore? Why would she want to smuggle drugs? What would happen to her now? Mrs Poon was devastated. Desperate, she phoned her other daughter, Mary, at work. When the tearful mother finally finished telling her what limited information she had over the phone, Mary too broke down in tears in the office. But the full horror of what was happening did not become apparent until the next day. Hong Kong newspapers widely reported the story of the arrest of the two girls. There was one piece of information the Poons did not know: if convicted, Yuen-chung couldbe hanged. ''Our worst fears were confirmed by a relative in Singapore. He told us on the phone that drug smuggling was 'a serious crime in the country'. He later mailed us a photocopy of the ordinance. I guess he was showing us in black and white what he could notbring himself to say on the phone,'' Mary said. It has been two years since the family has read those chilling words - in Singapore, the death sentence is mandatory for anyone trafficking in more than 15 grams of heroin. Those words remain the Poons' worst nightmare. In a quiet park near their home, Mr Poon spoke of his torment. ''I can still recite them. I have read them so many times now I can never forget them,'' he said. Last week, the words returned to haunt him. After more than two years of legal wrangling, Yuen-chung was sentenced to death by the Singapore High Court on September 28. Her friend Lam Hoi-ka was also found guilty but was spared the gallows because she was 171/2 years old at the time of the offence. Yuen-chung will be hanged if both her appeal against the conviction to the court of appeal and her submission of clemency to the president fail. The legal process is expected to take between six months and a year. The situation looks grim, as deadly precedents have already been set in Singapore. Two Hong Kong men were hanged for drug offences in July, and a man and woman from the territory face the same fate after being sentenced to death in another drug case lastmonth. It was late last Tuesday when news of the sentence was related to the Poons. The mother burst into tears. The father wept quietly in the privacy of his bedroom. Later, in their modestly decorated flat, the parents sat down with their son and daughter, and spoke to an outsider for the first time of their ordeal. Mary soon emerged as the unofficial spokesman. ''I have never seen my father cry,'' Mary said. ''But I know he has cried a few times since my sister's arrest. His eyes would swell up. He looks so different now from two years ago.'' Mr Poon pointed to a moth that had flown in through the window. The insect is a sign of bad luck. While the father has visibly aged, the ordeal has also taken a terrible toll on the mother whose health has deteriorated since the arrest. She complains of chest pains. ''My mother would say it felt as if somebody had stabbed her heart. She cries a lot. She does not talk much these days. She likes to scribble her thoughts in writing and put the papers away. The other day I saw her write on a piece of paper: 'I pray every night for my daughter's return'. I expect she does. But it is painful to see it in writing,'' Mary said. Now the parents are desperate. The moments of disbelief and denial have long gone, but they have not given up. ''We want to do as much as we can to help Yuen-chung. We have to help her to the very end. We have to hang on. We have to be strong. Life has gone on without her all these months now. But she is with us in our hearts. We want her to live - wherever she is,'' Mr Poon said. The mother said: ''I don't know what to do. I may die before she dies. But she is so young.'' ''She may or may not have done it,'' Mary said. ''My parents think everybody should be punished for his or her crime. ''But we are appealing for leniency. The law provides that any person below 18 cannot be sentenced to death. She was 18 years and 10 months old when this happened; and her friend 171/2. Her friend was sentenced to life imprisonment. Some people won't be mature enough to think until they are much older. My sister is a simple and naive girl who can do foolish things sometimes. I beg the authority to give her a chance,'' she said. Yuen-chung comes from a simple home. Her father, an office clerk, managed to save enough for the down-payment of a tiny but comfortable flat in a middle class neighbourhood 10 years ago. It was only recently that he paid off the mortgage. It was a struggle, but the family was happy. Yuen-chung's brother and sister are both white collar workers. Yuen-chung did not fancy office work. At 15 and after finishing secondary three education, she decided to enrol in a drawing course while working as a shop assistant. She draws well, especially simple cartoon characters. Her sister thinks she can go far if she is given a chance to develop her talent. On her secondary school report, her principal described her as ''sociable, honest and sincere''. She was also noted for her obedience. Yuen-chung was a member of the school's community youth club. Her friends said she would not miss any events organised by the club, including flag-selling days. At home, Yuen-chung's favourite pastime was cooking huge meals for the family. Her best dish was bean curd with minced pork in chili sauce. At weekends, she would volunteer to queue up for a table in a nearby restaurant so her family could join her for yum cha. She is also a Christian, and had for years been a regular church-goer until she left school. ''She loves us. She would do anything for us,'' Mary said. ''She would use her salary to buy us little presents. My mother is still wearing the ring she bought her on her birthday. How a girl like her would end up smuggling drugs baffles me. I thought these things only happened in movies, not to a simple family like ours.'' Mary said since her sister's arrest, she had refrained from asking her what exactly had happened. If Yuen-chung is to be believed, she and her friend are innocent victims of sophisticated drug traffickers who prey on unsuspecting tourists. Yuen-chung and Hoi-ka were stopped by an officer at the customs counter at Changi Airport on July 16, 1991. When the officer saw from their passports that they had arrived from Bangkok, he searched their bags. Slabs of heroin were found concealed in false bottoms of both bags. Both girls denied knowledge of the drug, said to be worth S$9 million (about HK$44 million). They said they had met a Chinese couple in Bangkok who befriended them by taking them out for dinners and sightseeing tours, and later bought suitcases for them. Yuen-chung and Hoi-ka said in their defence they did not suspect anything about the bags until their arrival in Singapore when customs officers checked them. ''I have to have total confidence in her. We are close sisters - emotionally and physically. We shared a room, and we would tell each other our darkest secrets. She would definitely tell me if she was in trouble,'' Mary said. ''All she said was she was going to spend a few nights with friends on Lamma. The next thing we knew she was already arrested. Maybe she was foolish. Maybe she met some bad people. But I have to trust her.'' Mary had been to Singapore twice, to visit her sister at Changi women's prison. The first time she went with her mother and her 70-year-old grandmother who broke down at the sight of Yuen-chung. ''It was a pitiful sight, and a nasty shock for my grandmother. She insisted on coming with us when she found out we were going to Singapore. She thought it was just a holiday. We did not tell her we were to visit Yuen-chung in prison until we were there, when we knew we could lie no more,'' she said. ''Yuen-chung asked after every one in the family. She asked after my father's tropical fish, and the plants. She wanted to know whether we had rearranged the furniture. I told her we had left her bed, her wardrobe, everything that belonged to her untouched. I told her we would wait for her to come home.'' Mary last visited Yuen-chung in June. This time she went on her own to save the rest of the family the trauma. According to Mary, Yuen-chung finds life at Changi bearable. She is not assigned prison work so she spends her days reading, drawing and singing. Mary would copy lyrics for Yuen-chung. Anita Mui Yim-fong's Bring Back My Happy Self is one of her favourites. But her most popular pastime is still to write letters to the family, and to re-read the hundreds of letters Mary has so far sent her. It is also in the letters Yuen-chung reveals her thoughts. She has remained strong throughout, and has taken on the role of convincing her parents she will survive the crisis. In one letter, Yuen-chung said: ''I have been dreaming a lot these days. There is one dream I cannot forget . . . ''I was walking on my own from Shekkipmei to Lam Tin. All the taxis I waved at on the way were out of service. In the end I still managed to get home. . . I knew I meant to be home earlier. ''This is a meaningful dream. If I have more of these dreams I will be much happier. To dream at home is of course the best thing that can happen to me.'' In the same letter Yuen-chung also spoke of her life in prison, and her faith in God. ''. . . I had a counselling session yesterday. The missionary is a nice woman. I only see her once every two weeks for about an hour but she is my only companion here. I tell her everything. She is a Christian . . . I only wish I could see her more. ''Tonight I pray. I also read the Bible. This simple, routine life I have led for 19 months now. Time flies. When do you think God will rescue me?'' In another letter, Yuen-chung told of her dreams to return home, and her thoughts of her family. ''I miss you all a lot. I am all right. Please don't worry about me. I pray everyday. I also read the Bible . . . Did I tell you I will be baptised? . . . I don't mind when as long as they will baptise me. She went on: ''How is father? Is he in good health? Tell him not to miss me. . . . How about mother? Tell her I miss her cooking. It is delicious . . . I miss very much my days at home but I will hang on to the very end. I will be patient. ''You are such a good sister. Wherever I go I will remember you because you have been so nice to me. Do you remember the days when you would tell me everything and I would listen to your thoughts? Those were the good old days in Hong Kong. Those were happy days. Although I will not be able to enjoy this with you now, [isn't it nice] we can still write to each other? ''One day we will be able to talk to each other again, just like before. ''I have received mother's letter. Be strong, be patient. This is what we need to do now. Do not worry.'' Mary said Yuen-chung still had her weak moments. Last week, when Mr Justice Mohidin Rubin called on all those present in court to stand before telling Yuen-chung she would ''be taken from here to a place of execution to be hanged'', she broke down. A friend who had witnessed the sentencing said the bespectacled Yuen-chung, in a white jacket over a yellow T-shirt which her sister had brought her during her last visit, had wanted to hold back her tears. ''I will never forget that moment when she burst into tears. It will always be on my mind. She managed to collect herself and waved goodbye to me in the end,'' the friend said. Mary said: ''My sister does not want to die. If she wanted, she would have killed herself in prison already. I am sure that is not the way she wants her life to end. She has known all along after her arrest the death sentence is mandatory. But she wants to live. She is hanging on to the last minute. I hope people will support her. I hope she will be allowed to live.''