Adoption can transform lives. Today, most children available for adoption have had a difficult start. Removed from birth parents and taken into care, many have experienced abuse and neglect which can leave them with complex mental health and/or developmental needs. Adoption can provide them with stable and loving homes.

But what happens when the challenges the adoptive family faces become overwhelming? And is there enough support available to the families who give a home to some of the most vulnerable children in society?

File on 4 hears from adoptive parents struggling to cope with their children's complex problems - and battling with the authorities to get the help they desperately need.

The charity Adoption UK thinks as many as a quarter of all adoptive families are in crisis and in need of professional help to keep their family together. But are adoptive parents given enough information about the challenges they are likely to face and when they do encounter problems, is there enough help available?

Two years ago, the government set up a special fund designed to help adoptive families in England access a range of post-adoption therapeutic services. To date, more than £52 million has been spent via the Adoption Support Fund. But where is the money going and are the treatments on offer proven to be effective?

The truth is that no one really knows how many adoptions are 'disrupted' or end up in full break down when the child is permanently returned to care. But when they do, it is devastating for everyone involved. We speak to families fighting to get the help they need to stay together.

Reporter: Alys Harte