Let me be frank: I didn’t have high hopes for “The Imaginarium of Doctor Parnassus.”

Like many, I’d first heard of the film in the wake of Heath Ledger’s tragic death two years ago. It was the movie he was working on at the time of his death, and filming was unfinished, leaving the film’s future in limbo.

The film features Ledger as a mysterious stranger saved from death by a troupe of traveling performers — a role made exponentially eerier by Ledger’s actual death.

In a daring choice, director Terry Gilliam recast Ledger with not one, but three actors: Johnny Depp, Jude Law and Colin Ferrell. Each plays Ledger once, during trips into the imaginarium, and the decision helps the film pay tribute to the fallen star.

Strangely, the film opens without Ledger. Instead, we meet Dr. Parnassus, played by Christopher Plummer, and learn about his bad habit of making bets with the devil, played by Tom Waits.

His latest wager is for his daughter, Valentina, played by Lily Cole. In order to keep the devil from taking her on her 16th birthday, Parnassus must collect five souls before the devil can do the same.

The battleground for this wager is the imaginarium, a dream-like world only Parnassus can create. Those who enter the imaginarium through his magical mirror are faced with their hopes, wishes and dreams — and temptations that could cost them their soul.

Unfortunately, between the exposition explaining this and Parnassus’ weak attempts to win souls by performing outside “fantastic” venues such as bar parking lots and street corners, the beginning of the film drags until the moment Valentina and her close friend Anton, played by Andrew Garfield, spot a man hanging under a bridge.

The man is Ledger, and as they try to revive him, it is as if they are pulling him back from beyond the grave for one final performance.

The movie now begins to gain focus, as Ledger is revealed to be a disgraced charity worker named Tony. Now Parnassus’ best hope, Tony quickly comes up with a scheme to modernize the show, taking the troupe from their Victorian-era premise into a 21st century exhibit in a shopping mall.

It’s here that Tony himself starts to enter the imaginarium as a guide and when Ledger is replaced by his three stand-ins. Depp is the first and by far the best at playing the character of Tony as Ledger would have done.

The scene is somewhat chilling at times, with Depp referencing stars who have found immortality by dying young like James Dean and Marilyn Monroe — references that resonate in the wake of Ledger’s own untimely death.

After Depp’s all-too-brief stint on stage, Ledger is replaced by Law, who is the weakest of the three stand-ins. Law’s biggest problem is he seems to play the character of Tony as he would, not as Ledger would, and it creates a sharp disconnect, especially in comparison to Depp.

Luckily, Law’s time onscreen is short, just long enough for Tony to reveal to Anton that he’s not quite the charitable man he appears to be. Ledger then gets a few more moments of screen time before entering the mirror one final time with Valentina in a last-minute effort to save her.

Farrell is the last to take on the role of Ledger-playing-Tony, and the final act of the film begins well with a jaunt into Valentina’s mind.

The imaginarium, and thus the movie, begins to fall into chaos as the truth behind Tony is revealed. The chaos is intentional, but it makes the film hard to follow and the plot nearly unravels entirely by the end.

Luckily for the movie, plot consistency and coherence is no longer the mission. The goal is now to pay tribute to the fallen Ledger, and both his scenes and those of his stand-ins do just that.

“Parnassus” isn’t a great movie in its own right. Though the acting is decent, having Ledger for the whole film could have given it a boost, and the structure and plot are somewhat flawed.

But it is wonderful in the sense that it is a great tribute to a lost actor, and that Gilliam’s “Imaginarium” brings Ledger back one last time to give us another chance to say goodbye.