"Fantastic Beasts and Where to Find Them" is essentially a Harry Potter movie without Potter. It is set in J K Rowling's "wizarding world", but in the New York of the 1920s, not in contemporary Britain. Despite the American setting, the main character Newt Scamander is British. He is referred to briefly in some of the Potter novels, but never actually appears in them. (Some of the Potter characters, such as Albus Dumbledore, are referred to, but do not actually appear, in this film).

The late zoologist Gerald Durrell once wrote a book entitled "A Zoo in My Luggage". As far as I am aware Durrell did not possess any magical abilities, and his title was not to be taken absolutely literally, but Newt Scamander is a man who quite literally does have a zoo in his luggage. When you're a wizard- to be exact, a magizoologist- fitting an entire menagerie of fabulous beasts into a suitcase is easier than it sounds. The difficulty is persuading them to stay there.

In 1926, Scamander arrives in New York en route to Arizona. He only intends to stay in the city for a short time, but things go awry when he loses his suitcase and several of his beasts manage to escape from it. The film then follows his adventures as he tries to recapture them with the aid of local witch Tina Goldstein and Jacob Kowalski, a "No-Maj" factory worker with ambitions to set up in business as a baker. ("No-Maj", short for "no magic", is the American term for a person without magical abilities, what in Britain would be called a "muggle". The maxim that America and Britain are two nations divided by a common language holds good even in the wizarding world).

As in the Potter films, the prevalent theme is that of good versus evil magic. Scamander, played by Eddie Redmayne as a shy, diffident young man, bats for the good side. Voldemort does not make an appearance, but we have another malevolent wizard, Gellert Grindelwald, to bat for Team Evil. Moreover, Scamander also has to face a problem which (apart from his unpleasant aunt and uncle) never bothered Harry Potter too much, namely malevolent muggles. Despite the existence of an International Statute of Secrecy, which forbids wizards from revealing their powers to the outside world, a militant group of American No-Majs known as the "second Salemers" have become aware of the presence of witches and wizards in their midst and are demanding the re-enactment of the anti-witchcraft laws and of the death penalty for witches. As a result the American magical community has become increasingly paranoid about secrecy, and breaches of security are punishable by death.

The film contains a certain amount of political satire at the expense of America, with parallels drawn between the wizarding world and real-life American politics. Both the "Second Salemers" and the more extreme factions inside MACUSA (the Magical Congress of the United States of America) seem deliberately designed to recall McCarthyism. The ban on American wizards marrying No-Majs, or even befriending or interacting socially with them, recalls the officially-sanctioned racial segregation of the "Jim Crow" era. A ban on magic wands is the equivalent of the Prohibition laws.

Satire is never going to be cutting-edge humour when it is directed at the politics, customs and institutions of several decades ago, but the film's main appeal does not lie in its satirical barbs, or even in its plot. What makes it something out of the ordinary are J. K. Rowling's remarkable imagination, and the visual imagination displayed by the film-makers in transferring her vision to the screen. The New York we see in this film is on the one hand recognisably the New York of the 1920s which we all recognise from dozens of gangster movies and on the other hand a strange, alien steampunk fantasy world, where strange, alien things can and do happen. Scamander's beasts are a weird and wonderful set of creatures which owe more to Rowling's imagination than they do to the traditional fabulous beasts (unicorns, dragons, etc.) of legends and fairy-tales. The film was directed by David Yates, who also made several of the Potter films, and who clearly has a visual imagination to compare with a Tim Burton or a Peter Jackson. There is a lot to enjoy here for any Potter-addict deprived of their regular fixes since the main franchise came to an end with "Deathly Hallows Part II" in 2011.