A couple on holiday witness a murder and are entrusted with information regarding a planned assasination. In order to prevent them passing the information to the authorities their child is kidnapped - they return to England and attempt to recover the child. This is the basic plot this remake shares with Hitchcock's classic 1935 original of this movie - the differences account for the very distinct nature of this excellent version.
The most important shift is in the casting - gone are the urbane English couple to be replaced with Jimmy Stewart and Doris Day as the all American applepie family (for once Hitchcock is not casting against type), and the emotional cataclysm of the kidnapping more forcefully brought home in this movie as Hitchcock allows himself time to develop the family relationships. He has also switched from the father-daughter relationship to a mother-son. Emotional depth is earned at the price of pace ( this version is much longer than the original).
The shifting of the opening scene from a studio mock-up of Switzerland to real life Morocco says a great deal about the production values of this version - and it certainly looks good. The London scenes too benefit from location shooting.The famous Albert Hall scene is much improved in this version with Hitchcock ratcheting up the tension in his usual style. So far so brilliant.
After the Albert Hall scene, however, the movie parts from its original, jettisoning the brilliant siege, and introducing a rather silly musical finale in the embassy. Lovers of Doris Day will relish her 'Que Sera Sera' (I prefer the Sly and the Family Stone version), but I do feel the movie tails off slightly.
It is, however, a very entertaining film with a flavour of its own - falling short of the original perhaps, but only by a whisker.