Suprisingly good adaption of Ira Lewin's novel. Even though it's Robert Wagner who is playing the lead you don't get too bothered since he's playing a very fishy and wimpy character.

Young Bud has just knocked up his girlfriend Dory and now has to get married to her, despite that Dory most probably will lost her inheritance of millions of dollars. But Bud has other plans then to get married to her. In fact he's not really that into her, or rather thinks she very annoying and now when she has screwed up his future, she must die! So he plans very carefully to fool Dory, to give her a lethal dose of "vitamine pills" and makes her to write a english translation of a spanish text "for his homework" which looks like a suicide note, which he sends to her father the same day.
But something goes wrong and Dory turns up as usual, by the time she should be dead and acts like normal, so then Bud has to think of a new idea as fast as he can, since he has already sent the note, and tricks her that he immediately wants to get married and asks her to meet him at the courthouse where he asks her if they can't go up to the roof and watch he world the last time as unmarried.
There he pushes her, to a certain death.

Now Bud's future is saved, but he starts to miss Dory's father's money.
So he soon starts to date Dory's older sister Ellen who like nobody else had no idea that he was dating Dory, and even less, killed her before he met Ellen.
But a friend of Ellen's recognises Bud from the college and the more he thinks of it, he has seen Bud with Dory various times before her death, and might have been her boyfriend. The problem is that Ellen is engaged and head over heals in love with Bud, and won't take her friend's advice to beware of him.

The movie was suprisingly well adapted like I said, even though I miss some details and I don't think it showed as well as in the book how extremely annoying Bud found Dory and how much he despised her and how cold blooded he killed her. And I found it very interesting that they never mention the word "abortion" in the movie, which would be very natural considering the circumstances, like they discuss a lot in the book but Dory refused, but I guess it would be controversal at that time to mention such a thing then, n'est-ce pas?
You´ll see a very young Joanne Woodward as Dory (before her marriage to Paul Newman) and Mary Astor as Bud's mother.
The movie is full of nice teenage-1950s atmosphere assisting with music score by both the legendary orchestera leaders Billy May, and Nelson Riddle (who both has produced Sinatra's two best albums).