In the years to come, there will certainly be some debate regarding whether the late Heath Ledger truly was on the verge of becoming one of Hollywood’s greats or whether his early death has led many to embellish the actor’s true talent. Yet, few would deny that the loss of this gifted individual at such a young age is a tragic one, and his final performance in “The Imaginarium of Doctor Parnassus,” an intoxicating visual spectacle that’s dripping with enchanting candy-colored madness, is not one to miss.

There was a point in time, however, where it seemed everyone would miss out on Ledger’s swan song. When the actor died during production of the film, director Terry Gilliam (“The Brothers Grimm”) was left with the unforeseeable task of finishing the film without one of his main characters. Nevertheless, Gilliam pushed on and managed to get by with a little help from Ledger’s friends.

In honor of the late actor, Johnny Depp (“Public Enemies”), Jude Law (“Sherlock Holmes”) and Colin Farrell (“Crazy Heart”) signed on to portray transformed versions of Ledger’s character, Tony, when he enters the imaginative realms of a magic mirror run by the mysterious mind of Doctor Parnassus. While such a massive restructuring would have sent most films down the path to disaster, anything is possible in the wacky world of Gilliam.

Teaming up with co-writer Charles McKeown for the first time since cult favorite “The Adventures of Baron Munchausen” in 1988, Gilliam brings to life the tale of Doctor Parnassus (Christopher Plummer, “The Last Station”), an immortal sage who is able to guide souls on a life-changing journey of imagination as the result of a bargain with Mr. Nick (musician Tom Waits), a personification of the Devil, who in turn gains ownership of Parnassus’ only child, Valentina (newcomer Lily Cole), when she turns 16. With Valentina’s fateful birthday only days away, Mr. Nick offers Parnassus one last chance to save his daughter if he can guide five souls and prevent them from giving into the Devil’s trickery before time runs out.

With its grand fantastical premise, Gilliam’s latest film is the perfect visual playground for a director who never stops short when it comes to providing viewers with the most dazzling of movie eye candy, a trait that fans have come to adore him for. Through Doctor Parnassus’ looking glass lies a world of candy cane hills, breathtaking cliffs that scrape a brilliant blue sky and jewel-toned rivers inhabited by fiery dragon-faced gondolas.

Yet, the film’s greatest treat turns bitter as soon as audiences find themselves back on the drab outside of the real world looking in at the magical imaginarium awaiting them in the mirror, wistfully longing to go back. But the film’s alluring visual effects aren’t all that’s lost upon leaving the realms of the mirror. The story takes a turn for the worse as well.

When in the real world, nothing happens. The Doctor’s travelling theatre troupe simply wanders from place to place, hoping to find a lost soul so they can enter the mirror once again — a feeling audiences can relate to. On the other hand, every time the characters go inside the mirror, a new nonsensical, yet captivating journey begins, and audiences are treated to the devilish charm and wit of Waits’ Mr. Nick as he tricks souls into taking the sinful way out of the mirror by hitting up Mr. Nick’s Lounge Bar or the One Nite Stand Motel.

However, there is one benefit to hanging out in the real world: it’s the only time you get to experience Ledger’s dashingly charming performance as Tony, a mysterious stranger who joins Parnassus’ troupe and attempts to win not only Valentina’s life back, but also her heart. While it’s a bit eerie at first to see Ledger performing on the silver screen, especially since when we first see him he’s hanging from a noose, by the end you find yourself wishing he had been around to portray the role in its entirety.

As far as Ledger’s stand-ins go, Depp performs admirably, perfectly channeling the nuances of the character Ledger strived to create, while Law and Farrell manage only to keep the character in motion without adding anything of substance to the role.

Although Ledger’s final role in “The Imaginarium of Doctor Parnassus” will ultimately be overshadowed by his psychotically brilliant turn as the Joker in “The Dark Knight,” his performance and Gilliam’s eye-catching imagination give the film enough firepower to burn through the dragging real world visuals and story, making this imaginarium one worth entering.

3 out of 5 stars.