Imagine the one you loved most has been killed by a terrorist bomb.

Imagine that the promises of politicians that justice will be done turn to ashes; that the police investigation stalls.

The bombers walk free - and they will strike again.

Then hopes of justice turn to thoughts of revenge - especially when the names of the terrorists were known to all - even 'the dogs in the streets'. The relatives of the slain take the law into their own hands. They are driven by guilt.

Maddy because she sent her two small children and her husband out onto the streets to meet their death. Rob because he had brought a little boy who had saved his life to Britain - only for him to be wantonly murdered.

Maddy and Rob - and the others - owe. And they will be avenged.