Revenge is a dish best served cold. But patience can be a tall order. He is one of the world's most ruthless terrorists, codenamed Saladin. He plans and executes devastating attacks and then, ghost-like, he disappears. Ten years ago he blew a plane out of the sky above New York - and now he's killed dozens in a London strike. But one of the latest victims is related to the acting head of MI5, who knows exactly...