The green face hangs in the Room of Horror and around it grows a living, baffling legend of mystery and murder. At 2.00 a.m. the Embankment fog is thick and black. Men are gathered round a body. The dead man was clubbed and then thrown into the Thames. Dick Shannon races back to Scotland Yard, which is humming with the latest news: the Queen of Finland's car has been held up in The Mall and her diamond chain has vanished into the fog...