The mysterious letter invited him to an interview for a job he'd never applied for. But at 37, his family life and medical career in ruins, Dr Mark Avedissian wasn't feeling like asking too many questions.Nor, it turned out, were British Intelligence, Avedissian's new employers, prepared to give many answers about his new role in their battle against terrorism. With minimal information they despatched him to America in the company of Kathleen, the...