I certainly wasn’t planning on feeding the fish; my intention was something else entirely. Frequently mentioned as a late high point in Hitchcock's career, Marnie deserves to be considered among his finest films overall! It’s an intricate and puzzling story dealing with buried desires and painful deceptions, and I consider it one of Hitchcock's more successful efforts. Tippi Hedren portrays Marnie, who is both a thief and a compulsive liar, but her difficulties run much deeper than they initially appear. Sean Connery plays Mark Rutland; he discovers Marnie stealing from his company’s safe, and we then observe them as they try to uncover the source of Marnie's inner turmoil—to the point that certain colors and Mark’s touch trigger episodes of intense fear in her. Using somber settings and shifting weather patterns, Hitchcock draws the viewer into Marnie's troubled mind, and Hedren gives a wonderfully restrained and affecting performance that suits the film well. As is typical, some scenes are pure Hitchcock; for instance, a disturbing sequence with a hand tapping on a window is particularly effective, while a scene involving a horse evokes emotion and guides the film toward its distinctive conclusion. It’s excellent work from the acclaimed director. 9/10

Source on TMDB