It would be fair to say that this is somewhat mediocre by Hitchcock standards, but the fact is mediocre for him is still a class act by anyone else's yardstick.
Cary Grant plays an ex cat burglar, who is accused of a string of jewel robberies in the French Riviera where he has retired. He decides to catch the thief in order to clear his own name, and latches onto the next likely victim, a wealthy American and her daughter - Grace Kelly.
For a Hitchcock movie, there are not so many surprises - you can see the ending coming long before it arrives, and the set pieces are not as spectacular as usual.. the thief catching is really just the Maguffin needed to capture some sparkling interplay between the charismatic Grant and the luminous Grace Kelly. It is the word play and even sexual tension that keep the film a favourite. The innuendo in the scene where Grace Kelly is urging Cary Grant to reach out and stroke and caress her...err... diamonds.. is superb, albeit a little undone by the over the top splicing with the fireworks outside - as amusing as that idea is.
Grant plays the charismatic and lithe ex burglar known as `the cat' in typical Grant mode, and Kelly is take-your-breath-away stunning in her Edith head costumes - as movie-star like as it is possible to be.
Some aspects seem dated - the back projection driving scenes, the studio bound house and water scenes.. however, Cannes and Nice are up there on display, making the Riviera as much a character as the stars, and the photography, as always in Hitch's movies, is gorgeous and richly coloured.
It has neither the edge, the suspense or the complexity of themes of Hitch's later work, but is an enjoyable piece of easy to watch fluff, that bears repeated viewings thanks to the director's flair, his stars luminescence and the sparkling interplays between them.