Johnnie: Your hair’s all wrong. It has such wonderful possibilities that I, well, I got excited. For the moment I became a passionate hairdresser.
Johnnie Aysgarth (Cary Grant) is a handsome/charming man who meets shy/straight-laced Lina McLaidlaw (Joan Fontaine) on a train. He’s a playboy who is seen in the society pages; she has a sheltered life and reads a lot. Soon, Johnnie sees Lina again in the English countryside; she looks lovely and carefree riding her horse. He goes w/ some local ladies to call on Lina; she is pleasantly surprised to see him. Lina’s parents (played by Cedric Hardwicke and Mae Whitty) caution her, as he’s son to a gentleman they knew, and considered to be “wild.” In no time, Johnnie and Lina (who he nicknames “Monkeyface”) fall in love and decide to elope. After a long honeymoon in Europe, the earnest young bride discovers her new husband’s true character; Johnnie is immature, a gambler, and deep in debt! He gets a job w/ an older cousin (played by Leo G. Carroll) as an estate agent, but that turns out badly. Eventually, Lina starts to become suspicious when Johnnie’s older/wealthy friend, Beaky (Nigel Bruce), is found dead while on business in Paris.
Johnnie: What do you think of me by contrast to your horse?
Lina: If I ever got the bit between your teeth, I’d have no trouble in handling you at all.
Sir Alfred Hitchcock said that an RKO executive ordered that all scenes in which Grant appeared menacing be cut from the movie. When the editing was completed, the movie ran only 55 mins. The scenes were later restored, b/c the director shot each piece of film so that there was only one way to edit them together properly. Hitch wanted Johnnie to be guilty, but the studio decided that the public wouldn’t accept Grant as a murderer. Hitch’s original ending had Johnnie killing Lina by poisoning her milk, but then convicting himself by mailing a letter that Lina had written. Donald Spoto, in The Dark Side Of Genius, disputes Hitch’s claim to have been overruled on the ending. Spoto writes that the early RKO treatment and memos between Hitch and the studio show that he desired to make a movie about a woman’s fantasy life.
He [Cary Grant] did kill me in the original cut, but at a preview, the audience simply refused to accept him as the murderer. -Joan Fontaine
Provokingly irresponsible, boyishly gay, and also oddly mysterious, as the role properly demands. -Bosley Crowther, NYT film critic, describing Grant’s character
This is the first time that Hitch served in the role of producer. I learned from movie critics/fans that Fontaine’s performance is the only Oscar-winning performance that Hitch directed! Grant (who became Hitch’s favorite leading man) felt that the director gave Fontaine preferential treatment to the detriment of his character. This movie was a big success, earning $1.8M at the box office. The couple’s pet dog is a Sealyham Terrier named “Johnnie,” and on of Hitch’s own dogs.
 The tension keeps building, and Fontaine’s performance allows the viewer to feel all of her fear and anxiety. Not everyone likes the way that it all ends, but it is worth seeing and deciding for yourself what you think about it.
 Grant is a perfect choice to play Johnnie Aysgard. He has the dark, handsome looks, that gleaming smile and loving charm and he literally sweeps Lina off her feet. His presence only vaguely suggests the menace hidden underneath and this is perfect for a convincing psychological, cerebral thriller.
And his presence is the reason this movie works as an excellent psychological thriller even if the ending is a letdown. Using an actor like Grant misleads the public into being sucked into the lighthearted tone of the first third of the story.
 We think we are watching the action unfold in the way typical of most Hollywood films… but in Suspicion we are watching the action from Lina’s point of view… from a very subjective POV. And we assume that Lina is the more mature, stable character in the film. But we then begin to see just how unstable she is, as she interprets every event to be an indication of Johnnie’s criminal nature, as her suspicion grows to paranoia. And let me tell you, Grant’s acting is top notch as he is loving and playful one minute, and menacing the next. Just the way he walks up a flight of stairs with a glass of milk is frightening. His demeanor completely cooperates with Lina’s imagination.
-Excerpts from IMDB reviews