Medical professionals Katy and Jonathan had been trying for a baby for eight long years. Finally after putting nearly every penny they had into IVF, they got their dream family - with twins. Ava and Tom were devoted, lively siblings and their parents were over the moon.

Then one day, when they were just three years old, everything changed. Their parents had been collecting their grandparents from the airport, while they were at nursery.

But 3pm came and went and no one arrived to take them home.

Instead the classroom assistant was told the heartbreaking news: Ava and Tom's parents and grandparents had been involved in a collision on the M25.

All four had died.

Ava's story tells the tragic tale of what happened next - as Cath, the mum of the twins' first foster family, falls in love with little Tom but has an inexplicable hatred for his sister, and after some difficult months, insists on handing her back.

As Louise steps in to try to help the abandoned little girl, she soon realises that Cath's anger may have been even worse than she realised: Ava's showing signs of physical abuse.

Can Louise expose Cath for what she is? And will the twins be reunited? It's a heartbreaking tale but with an ending that will restore your belief in good samaritans.