THE final piece of the Star Wars puzzle slots neatly into place with Episode III: Revenge of the Sith, a dark and emotionally intense chapter concentrating on the fall of Anakin Skywalker and his rebirth as the fearsome Darth Vader.

As the film's 12A certificate suggests, coupled with parental advice about "moderate fantasy violence and scenes of horror", this final journey into a galaxy far, far away may not be suitable for very small children. Or as the Jedi affectionately call them, the younglings.

At the end of Attack Of The Clones, Supreme Chancellor Palpatine (Ian McDiarmid) assumed control of the Republic, creating a great army to assist the dwindling forces of the Jedi in overthrowing a separatist movement led by ruthless Count Dooku (Christopher Lee).

As the Clone Wars enter their most critical stage, the Republic threatens to crumble under sustained attacks from the Dark Side.

In a daring move, fiendish droid leader General Grievous (voiced by Matthew Wood), a hideous conflation of metal and flesh, sweeps into Coruscant and kidnaps Palpatine.

Obi-Wan Kenobi (Ewan McGregor) and his hot-headed protege Anakin (Hayden Christensen) give chase, determined to thwart the separatist droid army's dastardly plan and return the Chancellor to the Galactic Senate.

Palpatine rewards Anakin for his valour by securing him a seat on the Jedi council, where the Chancellor currently has no power.

Like many of the council members, Yoda (Frank Oz) is suspicious of Palpatine's intentions; Mace Windu (Samuel L Jackson) makes their opposition quite clear when he tells Anakin: "You are on this council but we do not grant you the rank of Master."

Enraged by the distrust shown by the Jedis, and tormented by nightmarish visions of the death of his wife, Senator Padme Amidala (Natalie Portman), Anakin turns to Palpatine for guidance.

The Chancellor relates the story of Darth Plagueis the Wise, a Sith Lord who became so powerful, he discovered a way to manipulate midichlorians to cheat death.

"Is it possible to learn this power?" asks Anakin, glimpsing a way to save Padme.

"Not from a Jedi," replies the Chancellor ominously. And so begins young Skywalker's downfall.

Thankfully, the Jedi's plight is not without a glimmer of hope: Padme is pregnant with twins, who have a vital role to play in the galaxy's fate.

Revenge of the Sith is the most satisfying and compelling instalment of the recent trilogy.

Having already seen Episodes II and IV, we know the narrative arc of this bridging chapter.

However, writer-director George Lucas successfully keeps us in suspense until the spectacular finale on Mustafar, where Obi-Wan and Anakin lock lightsabres in the film's most eye-popping sequence, as the separatist base collapses into rivers of lava.

Lucas orchestrates a number of daring action sequences: the crash-landing of a Trade Federation cruiser, a devastating battle between droids and Wookiees at which Chewbacca makes a brief appearance.

An elegiac montage of Jedi murders is beautifully underscored by John Williams's soaring orchestral score and Anakin's metamorphosis from human to cloaked avenger is expertly intercut with Padme giving birth.

Computer special effects are generally excellent.

In particular, Yoda interacts seamlessly with the live action environments and his titanic battle with Darth Sidious is another highlight.

Occasionally, some of the technical wizardry doesn't quite pass muster: a giant lizard creature, which Obi-Wan Kenobi rides in pursuit of Grievous, doesn't obey all of the usual laws of physics and the perspective in some of the space battles seems slightly off.

Performances are strong, particularly Christensen and Portman as the doomed lovers, whose romance is poisoned by his ambition.

"The Jedi turned against me. Don't you turn against me!" screams the apprentice Jedi as he finally succumbs to the Dark Side.

"Anakin, you're breaking my heart!" wails Padme, no longer recognising the man she fell in love with.

Lucas has never been able to write dialogue and Revenge of the Sith is no different.

Yoda's grammatically muddled prophecies become more unintentionally funny as the film progresses and some of the heartfelt conversations between Anakin and Padme ring hollow.

Moreover, Anakin bows to the will of the Darth Sidious far too quickly - there's not enough internal conflict.

Dark triumphs too easily for his fall to be truly heartbreaking.

Rating: ****