"Step Down to Terror" is a remake of the Hitchcock film, "Shadow of a Doubt". This alone makes for a very tall order, as the original was quite a picture and Hitchcock such a famous director. But what makes it all worse is that the story itself seemed second-rate at best and really kept little of the suspense that made the original worth seeing.
Charles Drake plays a man on the run from the law...though exactly what he's done isn't clear until later in the film. He arrives in his old hometown after being gone six years. He says it's to see family and perhaps settle down there, but it's really a ruse...he's there to hide from the law.
At first, the family is thrilled he is home. However, his widowed sister-in-law goes from adoring him and welcoming his return to actually confronting him when she thinks he might be a murderer...which is amazingly dumb. From this point to the ending, it all goes VERY quickly and is really disappointing.
The bottom line is that this remake is inferior in every way and I can't think of a good reason to watch it. Stick with the original...unless you want to compare them and see why the Hitchcock version is simply better.