GM   It was the ever enigmatic Mr. Smith, dressed in his black suit and carrying his extremely large suitcase, powered by his tall, muscular frame, that sent Synapse off.    "Dover"   The channel tunnel had been shut. On the English side. There was a cover story, of course. Engineering works to ensure safety. All very reassuring. All completely false.    Nobody really knew what was going on, but it happened fast. An explosion and then...nothing. No trace of explosives. A flash for one se