Saturday afternoon: you're with the kids in the garden when the phone rings.

It's your best friend from school. Someone you haven't seen for a few years. It should be a friendly call catching up on old times.

But it's not.

This call is different. Your friend is panting with fear, his breaths coming in tortured, ragged gasps. Someone is inflicting terrible pain on him.

He cries out and then he utters six words that will change your life forever... the first two lines of your address.