Johnny inadvertently gets his sister-in-law Helen, Coleen Miller,to check out a newspaper that he ripped an article out of at the local public library and she sees in that newspaper that there's a killer on the loose and his latest victim was a woman from New Orleans who he murdered named Janice Dawson.
Sweet and kind Johnny gave Helen a ring with the initials J.D on it that he couldn't convincingly explain to her how those initials got there; a ring he won gambling Johnny told her. Later the policeman who came from out of state to arrest Johnny Mike Randall, Rod Taylor, calls Helen and tells her the good news that the killer who they were looking for who the police thought was Johnny was killed in a shoot out in New York City. This came across as pure gobbeldygook since how did the police know, just by him being dead, that he was the killer of the women that Johnny was suspected of killing. That still didn't explain Johnny's creepy and unnerving actions with Helen, who he tried to kill twice by having her fall down a stairway that he "fixed" and then later tried to kill her by putting a bottle of sleeping pills in her milk. I thought for a moment that Randall just wanted Helen as well as Johnny to know that he wasn't a suspect so that he would have his guard down and make it easier for the police to arrest him later.
Another thing that struck me was Johnny's mental state. Why would he throw suspicion on himself by tearing out the article about the killings since his name wasn't mentioned at all in the story? By him acting so guilty Johnny only made Helen suspect that he was the killer especially with the clue that he gave her. The ring with the initials G.D those of the killers victim in the article?
Charles Drake played a psycho killer to the hilt and almost as well as Anthony Perkins played Norman Bates in the movie "Psycho" two years later. The movie makers of "Step down to Terror" didn't seem to know how to end the picture with it having something like three different endings.
Ending #!. Johnny meekly giving himself up to the police. Ending #2. Johnny Cracking Randell's skull as he was about to arrest him. And Ending #3. Johnny driving away from the police and having his seven year-old nephew Doug,Ricky Kelman, come out of nowhere with his bike in front of Johnny's car and Johnny getting killed trying to avoid him with Helen in the car as a hostage surviving the crash.