The Alfred Hitchcock Hour - Season 3 Episode 8 Misadventure

Eva is the wife of a miserly businessman named Henry. Eva, who has been cheating on Henry, is tricked into planning a murder him by a mysterious stranger named George who gets into their house by pretending to be a gas man. The two plan the perfect crime, until the last possible moment when George decides to murder Eva and makes it look like her husband is responsible. George is really Colin the long lost brother of Henry. He framed his brother because, years ago, Henry wouldn't loan him money for his wife's expensive surgery. She died and he has been waiting for his revenge ever since.