The Salvation Army's Family Tracing Service restores family relationships by tracing long - and recently - lost relatives.
Hugh Dennis celebrates their work - begun 125 years ago by William Booth - as he meets some of the people who, out of the blue one Christmas, received the best Christmas present ever".
Full of Christmas music from Salvation Army choirs and bands, alongside other seasonal musical treats, Hugh shares poignant stories of painstaking searches and a significant number of happy endings.
We hear from mother and daughter, Kathleen and Claire.
Kathleen left Claire when she was a young toddler, having suffered a breakdown after years in an abusive relationship.
Over 30 years later Claire decided to look for her mum via the Salvation Army family tracing service; they have been reunited and spend so much time together you would never know they had been apart.
They tell their story and look forward to the future.
We also hear from father and daughter Steve and Rebecca.
After his divorce Steve kept in contact with his daughter Rebecca, but she was not coping with the tension in the family.
Rebecca asked him to stop visiting, Steve stayed away for a few years and then tried again to make contact, and things did not work out.
Twelve years later, Rebecca went to the Salvation Army to find her Dad, they are now reunited answering each others difficult questions and Steve is a proud grandad; a discovery that brought him great joy.
Alexandra - at the age of 53 decided to search for her father.
They'd been separated since she was 8 and she had only seen him a few times by the time she was a teenager.
The Salvation Army found her dad for her and, after writing to each other, they had their first meeting.
But it was to be the only one.
The Salvation Army enjoys an 85% success rate in their work yet they also have renowned expertise in dealing with the many issues raised by this important work; such as understanding why people lose touch, what it's like for those left behind, how families go about rebuilding trust and broken relationships and, critically, how to assist with making the all-important first contact.
Hugh Dennis celebrates the work of The Salvation Army's Family Tracing Service."