Cesar Romero ("O'Dell") is a visiting American sitting in a bar in London making a drink that wouldn't have looked out of place in Merlin's laboratory. He and the barman are trying to encourage the sceptical "Peggy" (Lois Maxwell) to partake when a police man enters the bar to use the phone to report an hit and run accident outside. She is expecting her brother - could he be the victim? Well it turns out he was, and now she and "O'Dell" determine to find out whether or not it was an accident and to get to the bottom of things. The mystery element of this is all a little procedural, but there is a bit of chemistry between Romero and Maxwell; there is quite a fun sub-plot between the American and his travel agent "Boswell" (Frank Birch) who is trying to repatriate him despite a pea-soup fog at the airport, and Geoffrey Keen finds himself with a more substantial part to deliver as the suspicious "Hampden". The aforementioned fog and the creepy Ivor Slaney score also contribute well to this by-the-numbers, but quite passable crime-noir.