The Catholic Church's past refusal to bury stillborn babies on holy ground, including a report on Milltown Cemetery in Belfast, where land containing unmarked graves was sold.

Across Britain and Ireland lie thousands of unmarked mass graves. People drive past them every day, not knowing that in them are buried tens of thousands of tiny stillborn babies. Hidden and secret, it is as though they never existed.

The babies ended up buried in these graves because of a piece of Catholic theology according to which babies who were stillborn or who died shortly after birth and that had not been baptised could be denied a cemetery burial. Their souls could not go to heaven but would remain in a place called Limbo. These are the so-called 'Limbo babies', stillborn babies born to Roman Catholic families who could not be buried in consecrated ground.

In a rare personal testimony, mums, dads and families describe the harsh effects of this centuries-old practice on their lives. Many of them secretly buried their children as close as they could to consecrated ground, or in desolate, beautiful locations they felt had been touched by God.

The film documents pioneering work by communities, clergy and people seeking change, such as at Milltown, Belfast's biggest Roman Catholic Cemetery. In Milltown, families made the shock discovery that their loved ones, some of them 'Limbo babies', were now buried in a wildlife reserve. Their mass unmarked graves had been sold through error by the cemetery. The film follows events as relatives of the Milltown babies began a weekly protest, the Catholic Church tried to seek resolution, and people began to arrive at the cemetery gates with stories of unresolved grief.

Finally, Fr Thomas Norris, from the powerful International Theological Commission which advises the Pope, describes the current Limbo situation. Does it still exist?