The Vanishing, but Alfred Hitchcock might very well be the only major director to redo an earlier effort so literally (unless one counts Howard Hawks retooling Rio Bravo as El Dorado and Rio Lobo).
This new version of The Man Who Knew Too Much, based on the 1934 version with the same title, retains the same basic setup and narrative development, but the details have been changed. Instead of a British couple whose daughter is kidnapped in Switzerland, the newer version centers on an American couple (Hitchcock's regular leading man James Stewart and Doris Day) whose son is kidnapped. In both movies, the kidnapped child is used as leverage on the parents to guarantee their silence about an assassination plot in London.
Dr. Ben McKenna (Stewart), his wife Jo (Day), and son Hank (Christopher Olsen) are vacationing in Morocco when they're helped out of a potentially tense situation by a friendly Frenchman Louis Bernard (Daniel Gelin). The next day, they witness Bernard, now wearing brown face makeup, being murdered, but before he dies, he whispers something in Ben's ear. Before the McKenna's realize it, Hank has been kidnapped by what they was a kindly English couple, the Draytons (Bernard Miles and Brenda De Manzie). With the cryptic information they have, the McKennas fly to London, caught between the police who demand to have it and the conspirators who threaten to kill Hank if they talk to the police.
Hitchcock was famous for his use of humor, but curiously,
that element is not on display here. Perhaps Hitchcock believed that
given the subject matter - an abducted child - it might have been
inappropriate (not that that hasn't stopped him before). The movie's
only humor is an inside joke with composer Bernard Herman appearing as himself to
conduct a symphony in Albert Hall for the musically-charged climax and
the denouement involving some very patient dinner guests. The
emphasis here seems to be more on the family in peril.
Hitchcock favored the man-wrongfully-accused trope, the innocent man on the run for the crime he didn't commit who would more often than not find help with a woman along for the ride, but in The Man Who Knew Too Much, the formula is shaken up a bit. The heroes aren't accused of any crime that drives the plot, but they are on their own with no help from the police. In addition, more so for Hitckcock, the wife, despite being setup as the standard flimsy, turns out to be the more heroic one.
Jimmy Stewart, at his usual "aw shucks" charming, is an open book to strangers. Ben practically tells his life story to Bernard and where they'll be staying, and it is Jo who eyes the Frenchman with suspicious and correctly notes he hasn't reciprocated with any info about himself. She's the one who notices the Drayons when they begin eying the McKennas. When Hank is kidnapped, Ben initially keeps the knowledge to himself and refuses to tell Jo until after she's taken a sedative. It looks like he's the one who's going to take charge, demand answers, and find their son, but for the longest time, he's ineffectual. It's Jo who realizes the name given to them by Bernard is not a person but a church, and it's Jo who is present at the assassination attempt and the one to be involved with stopping it. Ben, trying to force his way through to warn the intended target, is rebuffed and denied entry. Motherly love outweighs manly pride.
The orchestra scene is a masterful sequence, and really, nothing else in the movie could top it. Unfortunately, it occurs with another 30 minutes to go with the kidnapping still to be resolved. The scenes in the embassy and the sneaking around just don't have the same energy or power. Also hurting the movie is the lack of a great villain. By their nature, the villains are somewhat anonymous, but the original film had Peter Lorre revealed as the mastermind. Here, there's no equivalent.