The mysterious Shadow has blackmailed several high profile people who have then benn killed or commited suicide. The chief of Scotland Yard is baffled, and goes to his country mansion. A motley group of people stay at the house in the fog and are terrorised by the Shadow. This is a country house style thriller, though the plot is not great and the comic lines from Henry Kendall are incongruous to the plot. THe best performance is from Elizabeth Allan, although she did better work in other films.