We're supposed to have heard of Prince Valiant (PG). No, me neither. So who is he? In situations like this, the ignorant resort to their press notes. On page 16, the movie's star Stephen Moyer describes him as "a cross between Dudley Moore and Sir Lancelot". Um-hum. So, it's King Arthur II: on the Rocks, maybe? On page 12, producer Carsten Lorenz explains that "like James Bond, Valiant is concerned with justice and truth. He's Generation X, medieval style." Aha, then he's a coke-snorting, Martini- swilling round-tabler who's married a lot of tall people?

Rather disappointingly, Prince Valiant turns out to be a US comic strip character, an Arthurian swashbuckler previously impersonated in film by Robert Wagner and a pudding-basin wig. Created by Harold R Foster, the cartoon has doled out its cheerfully anachronistic hokum since 1937. The new movie - a muddled Anglo-German-Irish co-production - attempts the same jolly mangling of myth and history: crossbow-wielding Viking warriors steal Excalibur, but - cunningly - leave a kilt behind at the crime scene. "Tartan!" cries a knight with a talent for deductive reasoning. "It's the bloody Scots!" King Arthur (Edward Fox, giving a performance worthy of Roger Moore) orders an immediate counter-attack, and while the British fight among themselves, Eurobaddies snarl and strut in a stronghold staffed by Hell's Angels and pre-Reformation lap-dancers. They're an attractively peculiar line-up: Sligon the Usurper (an incomprehensible Udo Kier) is Eisenstein's Ivan the Terrible in a see-through shortie tabard. Thonged megalomaniac Thagnar of Thule (Thomas Kretschmann) is a ton of Teutonic muscle who might happily have been given the line, "For you, Tommy, ze Middle Ages are over!" And Joanna Lumley hams it up as Morgan Le Fey (sic) - though she gets little to do but to stride around in black leather, demonstrating the width of her mouth. She's monstrously wasted, and not in the Stolly-Bolly sense.

There are other odd pleasures on offer, like Chesney Hawkes in a tiny cameo as "Stable Boy". Oh, you must remember him. Anorexic-looking Jason Donovan type with prominent beauty spot who - despite having a name like part of the Cotswolds - got to Number One in 1991. Though he gets big billing in the film's opening titles, Ches's one-and-only line goes something like, "But Princess Ilene, your father told me not to let you get anywhere near this horse." It was over so quickly I didn't have time to write it down. His five-second appearance should serve as a warning to boy balladeers wondering if pop will provide them with a stable job.

I have more ignorance to confess: I didn't see either of the first two Home Alone films. My colleagues tell me that they were about a child who set diabolical traps for American character actors, which leads me to believe they were part of the Omen series. Home Alone 3 (PG) sets up house without Macaulay Culkin or director John Hughes, their places taken by Alex D Linz (a mop-topped urchin with the voice of an 80-a-day man) and Raja Gosnell, editor on the previous instalments. And there does seem to be a Satanic element: "If you're ready to see Hell, come on up and ring my bell", blares the theme song, as a gang of Slavic criminals pull up in search of a military microchip that has found its way into Alex's toy box.

With these East European terrorists using hi-tech devices to invade American domestic space, Gosnell evokes the sort of political symbolism familiar from Cold War sci-fi: the spectre of post-communist chaos haunts the gravel driveway of suburbia. Though the film constructs a kind of sub- patriotic sentimentality around Alex's home, its plot relies on his family's air of dysfunction to supply the drama of abandonment promised by the title. His brother and sister (Seth Smith and Scarlett Johansson) are cruel and spiteful; his mother (Haviland Morris) keeps in touch via mobiles, pagers, e-mail and fax; his father (Kevin Kilner) attempts to placate him in his neglect by promising to "bring the TV up from the Family Room". Family Room? Do people really use expressions like that? No wonder they're in trouble.

As with many children's films, the violent scenes are the most satisfying. Like some avenging imp from a stalk-and-slash flick, Alex greets his victims with electrocution, infects them with chickenpox, douses them in liquid excrement, drops dumb-bells on their heads from a great height and sends the whirring blades of a lawnmower hurtling towards their faces. I must admit I was extremely engaged by this section of the film, particularly a scene involving a pet rat and the groin of the villainous Mr Jurnigan (Lenny von Dohlen), which reminded me of a similar moment from American Psycho. All of which leads me to expect that in Home Alone 4, little Alex Linz will be putting Schubert on the gramophone and snapping electrodes upon the sex organs of his adversaries.

The third school-holiday release is George of the Jungle (U), based on another American cartoon I can't remember ever having seen. A parody of Tarzan, it features Brendan Fraser as the wide-eyed arboreal foundling of the title, and John Cleese as the voice of his simian mentor, Ape. Cleese's lines don't deliver the laughs that the improvisational talents of Johnny Morris might have brought to the part, and the film's best comic idea - George's inability to distinguish between men and women - is underexploited. For Christmas entertainment, The Borrowers remains top banana.

There's just space to mention what's available for grown-up cinemagoers: Kiss Me Guido (15) is a weakly-plotted comedy of sexual errors, redeemed by bitchy dialogue and attractive performances. Altogether more substantial is Close-Up (no cert), a compassionate, tricksy work by Iranian director Abbas Kiarostami. Based on a real case, and often resembling documentary, the film tells how unemployed printer Hossain Sabzian (played by himself) impersonates Iranian movie director Mohsen Makhmalbaf (who also features in the cast). Sabzian is charged with fraud, but for him, imposture has become an act of tenderness - because Makhmalbaf's films have spoken for the dispossessed, he's somehow returning the favour by speaking for the director. Kiarostami loops his time-structure, allowing the camera - rather like Makhmalbaf - to be in two places simultaneously. And with its thoughtful courtroom drama and warm, generous conclusion, it's the only film you'll ever see that suggests it might be rather nice to go on trial in Tehran.

Cinema details: Going Out, page 10.