What’s striking—and revealing—about this sequel to the smash 2005 adaptation of the first volume in C.S. Lewis’ “Chronicles of Narnia” series, “The Lion, the Witch and the Wardrobe,” is the background score by Harry Gregson-Williams. Throughout “Prince Caspian,” the overemphatic music keeps telling us to be awestruck, but the movie itself stubbornly lacks grandeur. Given the fact that it was shot in gorgeous locations in New Zealand and Eastern Europe and boasts big crowd scenes, impressive sets and fine visual effects, blame has to rest on director Andrew Adamson, who repeats his bland, sluggish work from the initial installment and (along with new cinematographer Karl Walter Lindenlauer) doesn’t frame the sequences with much distinction. Worse, once again he fails to energize his cast, so that the young heroes come off as bland and ill-at-ease and the villains solemnly smarmy. Simply put, the guy’s no Peter Jackson—who’s the standard-setter in this fantasy-world genre.

The plot of “Caspian” takes up a human year after the events of the first film, when the Pevensie children—older bro Peter (William Moseley), older sis Susan (Anna Popplewell), younger bro Edmund (Skander Keynes) and little Lucy (Georgie Henley) back home in wartime London. They’re whisked back to Narnia by a summons from the magical horn blown by Caspian (boyishly handsome newcomer Ben Barnes), who’s just escaped an attempt by his evil uncle Miraz (Sergio Castellitto) to have him assassinated. (Miraz’s wife, you see, has just given birth to a son, and Miraz wants Caspian, the rightful heir, out of the way so that he can seize the crown himself and initiate a dynasty.)

In their alternate world, the children find that much has changed. It’s more than a thousand years since their last visit; and all the dwarves and magical critters have been exiled to the forest by the conquering Telmarine race to which Miraz and Caspian belong. A few of the supposedly extinct Narnians befriend the on-the-run Caspian, and soon they’ve linked up with the Pevensies to build an army, restore the prince to his rightful throne, and bring about a political rapprochement between the Telmarines and the Narnians. The big questions are whether Peter can overcome his recklessness to become a true leader, whether Caspian can avoid temptation (courtesy of a cameo by Tilda Swinton’s White Witch) and gain the wisdom to rule justly, and whether Lucy’s insistence that she sees the long-absent Aslan—the savior lion—is more than wishful thinking (something her siblings seriously doubt).

Everything is resolved in battle sequences that make up the bulk of the latter reels of the picture, which is even longer than its sluggardly predecessor. The first is a botched attempt to stealthily take Miraz’s castle—the result of Peter’s rashness—during which it’s revealed that Miraz also killed his brother, Caspian’s father. (The obvious debt to “Hamlet” is thus pushed home with a vengeance, so to speak.) This sequence is played, as is much of the picture, in dank lighting, obscuring the action. There follows a one-on-one swordfight between Peter and Miraz, which has a certain brutal flair but is overly extended, with Miraz calling entirely too many time-outs and Peter ridiculously obliging. And a massed battle follows, with Miraz replaced by the treacherous Lord Sopespian (Damian Alcazar) at the head of the Telmarine troops and a few more characters from the first film finally making their long-delayed appearance. This is a big sequence, to be sure, but as montage it leaves much to be desired; here Adamson demonstrates that he he’s no Eisenstein or Kubrick, either.

If the big set-pieces fail to have the desired impact, the script’s religious references are hammered home with entirely too much more. The whole Lucy business is an obvious nod to the Gospel story of the apostles’ dubiousness over Mary Magdalene’s initial sighting of the resurrected Christ. The entire Peter scenario is drawn from the imperfections that Scripture draws in the original Rock. And the big final battle concludes with an oddball confrontation at a river that’s clearly modeled after the Red Sea disaster of the pharaoh’s chariots. (And one has to say that even forty years ago Cecil B. DeMille did it better.)

Among the menagerie of visual critters on display here, the one bound to score with crowds is the sword-wielding mouse voiced by Eddie Izzard, who may be a copy of Antonio Banderas’ Puss ’n Boots is no less energizing for that. Peter Dinklage also has his moments as the sour dwarf Trumpkin, though one feels he could have made more of an impression if he’d been allowed to let loose. But the full-sized human cast is a disappointment. The young actor playing the Pevensies have grown somewhat in the roles, but Moseley seems stilted at times (though he does the swordfight well), Popplewell is a mite staid, and Henley overdoes the cuteness; best of the lot is Keynes, who’s developing a darkly brooding but vulnerable presence that suggests he could have a career beyond these films. Barnes is appealing enough to make the teeny-bopper set swoon, but lacks the swashbuckling charisma Caspian really demands; he’s just a couple sizes smaller than needed. (The fact that he’s compelled to wear unattractive costumes—something fairly constant throughout, compliments of designer Isis Mussenden, is also a drawback.)

Barnes also has to use a southern Mediterranean accent common to all the Telmarines that make the whole palace bunch look—and sound—like a parody of the early modern Spanish court. Though some of them are actually played by Italians, Castellitto’s Miraz, Alicia Borrachero’s Queen Prunaprismia, Damian Alcazar’s Sopespian and Pierfrancesco Favino’s General Glozelle all seem to have wandered in from the entourage of Philip II depicted in Shekhar Kapur’s “Elizabeth: The Golden Age”—all swarthy and malevolent and almost comically treacherous. It’s not a particularly imaginative way of distinguishing them from the Narnians (or the veddy British Pevensies). The only palace-dweller to escape the unfortunate quality is Vincent Grass as Caspian’s enlightened teacher; under his heavy beard he looks like a near dead ringer for John Rhys-Davies.

Unfortunately, that resemblance only brings “The Lord of the Rings” back to mind, and the comparison is fatal. Adamson’s series is in the same mold, but beside Jackson’s masterful achievement it seems puny and forgettable. As a summer popcorn movie suitable for family viewing, “Prince Caspian” will probably suffice for most of the target audience, but it’s not one of those sequels that improves radically on its predecessor (like “The Empire Strikes Back” and “Spider-Man 2”), which—to be honest—wasn’t all that good to begin with.