Here it is, the synopsis for my cancelled Ep. III rewrite. As this was the least thought-out of my rewrites, I don't have much of a cohesive plot to share, just bits and pieces of the details I'd come up with, so forgive me for any incompleteness/disjointedness present.

Star Wars: Episode III - A Lost Hope

Timeframe: 19 BBY (about sixteen years after Episode II)

The Clone Wars are long over, but the galaxy is still not at peace. The Republic is now at war with the Confederacy of Independent Systems, a large secessionist faction lead by the fallen Jedi Master Jard Dooku.

Cos Palpatine has been elected Supreme Chancellor of the Republic.

Anakin Skywalker now works for Palpatine as his most trusted bodyguard.

The Nabu have completely abandoned monarchal rule for a strictly autonomous democracy. As such, Amidala Naberrie is no longer the Queen of Nabu.

Anakin and Amidala are man and wife, living on Coruscant.

The Jedi Order is in turmoil, torn between their service to an increasingly corrupt Senate and Chancellor and their loyalty to the Republic. As a result, many Jedi have abandoned the Order to fight for the Separatists.

Palpatine, fearing the Jedi may hold treasonous sentiments toward him, places Anakin on the Jedi Council to keep his eye on them.

A Separatist fleet attacks Coruscant, and Palpatine is captured and taken prisoner aboard the warship Invisible Hand.

Anakin is reunited with his former teacher Obi-Wan Kenobi. Together they infiltrate the Invisible Hand, where they fight their way through Dooku's rogue Jedi acolytes and apprentice Asajj Ventress to where Palpatine is detained. The two Jedi confront Dooku, engaging him with their lightsabers. Soon, Obi-Wan is seriously wounded and drops out of the fight, leaving Anakin to battle Dooku alone. Anakin eventually triumphs, cutting Dooku's hands off and bringing him to his knees. It is at that point that Dooku reveals to Anakin that Palpatine is the Dark Lord of the Sith, and that together they can destroy him and end his tyranny before it can begin. Palpatine admits to being a Sith, but tells Anakin that he has the power to bring an end to the endless conflict ravaging the galaxy, and that killing him will bring nothing but further chaos. Anakin decides to side with Palpatine and decapitates Dooku, becoming Palpatine's Sith apprentice. With that, the two escape the ship with an unconscious Obi-Wan in tow; unbeknownst to them both, however, Obi-Wan overheard Palpatine's confession before passing out, and is now aware of the Chancellor's true nature.

Obi-Wan eventually regains consciousness, and informs the Jedi Council of Palpatine's Sith nature. Mace Windu with a few fellow Jedi then go to arrest Palpatine at his office. As they do so, though, Anakin draws his lightsaber and attacks them. He quickly bests Windu's retinue, but fails to beat down the seasoned Jedi Master. Anakin collapses, defenseless before Windu's blade. At that point Palpatine, who has been silently watching this duel unfold, intervenes, unleashing his potent Force lightning upon the Jedi. Windu braces himself against the barrage, and soon pushes it back, knocking Palpatine back and down. Windu then, enraged, goes to strike the Sith Lord down before he can regain his senses. Before the Jedi's blade can make contact, Anakin re-enters the fray, igniting his lightsaber and slicing Windu's hand off. Palpatine takes advantage of Windu's sudden defenselessness, and finishes the Jedi Master off with a second volley of Force lightning.

Palpatine declares that the Jedi Council can no longer be trusted, and charges Anakin with the razing of the Jedi Temple. With a retinue of stormtroopers, Anakin lays siege to the Temple, slaying all the Jedi Knights and Masters they find, subdueing and imprisoning the apprentices for future indoctrination in serve to Palpatine. Obi-Wan and Yoda manage to survive the pogrom, and go into hiding.

The two Jedi make contact with Amidala, and inform her of Anakin's fall to the dark side. Together, they convince her into leading the ex-Jedi into a trap. She informs Anakin that Obi-Wan and Yoda are on the molten world of Mustafar, and he takes this information to Palpatine. Together, they journey to the hellish planet to confront the Jedi.

Anakin meets Obi-Wan on Mustafar. Obi-Wan entreats Anakin to leave Palpatine, that he knows he isn't a complete monster, that it isn't too late to turn back from the dark side. Anakin refuses to listen, stating that the power of the dark side is the only power which can aid him in bringing peace to the Republic. In the end, the two fail to resolve their differences, and engage in a lightsaber duel. Eventually Anakin oversteps, losing his right hand and lightsaber to Obi-Wan, and tumbles over the side of a ravine. He grabs hold of an outcropping rock, but before Obi-Wan can come to his aid and pull him up, he loses his grip and falls into the river of lava far below.

Also on Mustafar, Yoda encounters Palpatine with an entourage of crimson-garbed Royal Guards. The Jedi Master swiftly bests the Guards, but finds Palpatine to be more than a match for him. The two engage in a Force duel, but in the end neither master of the Force and overcome the other, and their battle comes to a stalemate.

Anakin, through the use of the Force, survives his plunge into the magma, but most of his body has been burnt away. Palpatine finds his dying apprentice, and whisks him away to safety.

Yoda and Obi-Wan meet with Amidala again on Coruscant. She reveals to them the fact that she is pregnant with twins, and plans to leave Anakin. The three depart the city-planet.

Anakin Skywalker is brought to a medical centre, where bionic parts are grafted to his ravaged flesh, transforming him into an monstrosity of black armour and machinery. Once the transformation is complete, he enquires Palpatine as to the whereabouts of Amidala; at that point the Chancellor reveals that Amidala has left him, vanishing without a trace. Anakin, dismayed, roars with anguish and collapses to his knees, enraged and hurt.

Months pass, and Amidala gives birth to the twins, Luke and Leia Skywalker. She along with the Jedi decide to seperate the twins to protect them from Anakin and Palpatine. Amidala and Obi-Wan will take Leia to Alderaan to be raised by Bail and Breha Organa, where they will both watch over the girl, while Yoda will take Luke and journey to the swamp world of Dagobah.

As we come to an end, we see Imperial Star Destroyers in pursuit of Jedi starfighters outside the orbit of a large green world. Aboard one of the Star Destroyers we find Palpatine, now the Emperor of the newly formed Empire, looking out into space at the fleeing ships. Anakin enters the bridge, now fully dressed in his black robes, reborn as the Dark Lord of the Sith Darth Vader. Vader joins Palpatine, and together they look out into space, perpared to track down and destroy all the Jedi scattered throughout the galaxy who will refuse to bow to their will. The end.