Another day, another comic book movie. Given the commercial success of "X-Men", it was as certain as the sky that Marvel's gaggle of genetically mutated superheroes would be back for seconds.

Part one, in fact, was less a movie than a marketing exercise: cramming as many franchise-friendly figures as possible into 104 fraught, forgettable minutes.

"X-Men 2" shares its predecessor's problems of story and self-containment: there's a hyperactive narrative and too much assumed knowledge. Whatever its merits as part of a series, it struggles to satisfy as a stand alone movie. If you haven't seen "X-Men", the character powers and motivations may mystify you.

To fill you in, then. A new breed of humanity has evolved: mutants. "Normal" people are terrified of these outsiders, who are each endowed with a particular power (eg telekinesis, teleportation, or the ability to control the weather - watch out John Kettley).

There are two superpowers amid the superfreaks: the dogooders led by Professor Xavier (Patrick Stewart), and the mutant-supremacists led by Magneto (Ian McKellen). Into this infighting juts General Stryker (Brian Cox), charged by the US president with sorting out the mutant problem.

Given the screenwriters didn't bother with a coherent story, it doesn't deserve to be explicated here (there's a plothole you could fly the X-Jet through). Best to suspend sense, savour the set-pieces, and mull over your favourite mutant.

Wolverine makes the movie - a wry, raw, charismatic character, embodied by the excellent Hugh Jackman. The shape-shifting Mystique (Rebecca Romijn-Stamos) is equally attention-grabbing, while religious blue demon Nightcrawler (Alan Cumming) is the pick of the newbies.

McKellen has a right laugh hamming it up as the magnetic villain; Cox is magnificent; and Famke Janssen impresses in a confused role.

If only the plot matched the performances, "X-Men 2" could rival "Spider-Man" in the Marvel-lous movie stakes.

As is, it merely points to the franchise's potential. The next step in evolution? Hardly. But it could be the missing link.