This features an entertaining cast, a speeding train and some evil Nazis - and passes 90 minutes really quite well. It's down to the eponymous policeman (Gordon Harker) and his enthusiastic but bumbling, sidekick "Bingham" (Alastair Sim) to track down some army supplies that are being sold on the black market. Quickly, though, they release there is something much more sinister going on - and a perilous investigation into fifth columnists who have an uniquely innovative way of smuggling secrets out of Britain is soon underway. Can he and "Bingham" thwart this cunning subterfuge? The story is well conceived, with both - and a rather untrustworthy "Mrs. Wiklinson" (Phyllis Calvert) keeping this cat and mouse game interesting and enjoyable to watch. Like the train, it doesn't hang about - and the ending is not quite what I was expecting.