Ruby's Parker's retirement hangs like a dark cloud over MI7. She herself has only a vague idea what the future might hold - both personally, and in terms of national security. But for many of her team, she's irreplaceable. To cap it all, there's a massive organisational overhaul on the cards at Thames House. Everyone's nervous, and with good reason. In the middle of all this uncertainty, there's an assassin at large. He's already...