Shocking new crime figures have revealed as many as 50,000 children are going missing from the streets of India every year.
Campaigners claim the youngsters are often 'stolen' by criminal gangs to fuel a growing black market in child labour and prostitution.
For the parents of the victims the not knowing what has happened to their son or daughter is often the hardest part.
Kunwar Pal is overcome with grief. His 12-year-old son Ravi went out for a bike ride two years ago but never returned.
He said: "My life revolved around my son but since he disappeared I have lost everything including my happiness and my job."
It is the poorest families who are most at risk from the growing problem.
Children from the slums are easily snatched from the streets as their parents are often both working and struggling to make ends meet.
One of the worst affected areas is New Delhi.
According to recent crime data, as many as 20 children go missing in the capital every day and at least five of them are never traced.
The police say their job as investigators is made much more difficult because poorer parents often do not even have a photograph of their missing child.
They have now launched a scheme using theatre to try and educate children about the dangers of stranger danger.
They are also taking portraits of children in the areas the human traffickers target, so if the worst does happen, the parents at least have a photographic record of the child they can show detectives.
But many parents with missing children say the police are simply not doing enough.
Tajwar Sultana says her granddaughter, who was three when she vanished in 2009, is just another statistic for the police to ignore.
The family were at a wedding party when their little girl was taken.
She said: "Her mother is in a terrible state. Our situation is worse than death."
There are now demands for tougher punishments for the human traffickers who prey on India's children.
But activists fear as the police struggle with the enormity of the challenge the problem of India's 'stolen' sons and daughters will continue to get worse.