Said devotion to the product is the difference between greed (or whatever it is that drives studios to make expensive movies in the hope of expensive returns) and obligation, the latter of which is the driving force behind Pirates of the Caribbean: On Stranger Tides. This slightly belated fourth installment ditches Orlando Bloom's Will and Keira Knightley's Elizabeth, focusing entirely on Jack Sparrow (Johnny Depp), still engaged in a trip to the Fountain of Youth that does not at any time go in a straight line from point A to point B.

Sparrow's journey is not a solo journey; he is flanked by not one but three groups of people, all after the same target. Primarily, he finds himself a prisoner of the evil, scheming Blackbeard (Ian McShane), who wields a sword that allows him to telekinetically control pirate ships, and raise zombies from the dead. More alarming to Jack personally is Blackbeard's daughter Angelica (Penelope Cruz), a former flame who he wronged and ditched -- a series of events she has not yet gotten over. Steps behind Blackbeard is Barbossa (Geoffrey Rush), sporting a peg leg and official government garb instead of his usual pirate hat, and finally ahead of both parties, a group of Spanish ships proceed with an unshakable focus, turning the entire trek into a chase to get there first.

In the absence of Will and Elizabeth, the screenplay by Ted Elliott and Terry Rossio makes the unwise decision to make Jack the lead character. Jack is meant to be spontaneous, the kind of guy who does the trick play while noble-minded heroes are forced to choose between a rock and a hard place, but when Jack's decisions and goals drive the narrative forward, he can only be as spontaneous as the story allows. Early in the film, Jack gets wind that someone else claiming to be Jack Sparrow is recruiting pirates for a crew. In a different movie, Sparrow would find his own ship and confront the impostor whenever fate brought them together, but here, he heads straight to the impostor, because he has to for the film's events to be set in motion.

The script also labors to put Jack into positions where Depp can do his schtick, but most of the scenes are a stretch and some don't even make sense. In one, Sparrow, Blackbeard, and Angelica arrive at a cliff from which someone needs to jump. Sparrow doesn't want to, but he doesn't want Angelica to either, creating an argument until Blackbeard forces Jack to choose between one of several potentially loaded revolvers to fire at Angelica. The scene is a mess: there's no reason for Angelica to stand around while Jack fires guns at her; the gun threat seems to have no solution in which Jack can win (and if he does, it's not like Blackbeard will jump); and the whole thing ends with the implication that Blackbeard would've let Jack shoot Angelica, for no reason at all. As for the schtick itself, Depp straddles the line between good and bad. Most of it ranges from predictable to slightly annoying, and Jack's written romantic history is at odds with the ambiguously asexual way Depp continues to play him, but for what it's worth, he still seems to enjoy the character, especially in the scenes where he gets a chance to bounce off of his co-stars.

Meanwhile, a poor attempt is made to build up a mermaid played by Astrid Berges-Frisbey and a religious man played by Sam Claflin, presumably because the other films had characters that were not Jack that were also important. Since none of the story really hinges on either one of them, each time the film cuts to them, it's a drain on the movie's energy; the audience does not know these characters well enough to be invested in them, and the script does not have any interest in elaborating on them. Barbossa's presence fares a little better, but his character's motivation isn't strong enough or revealed early enough to give him any real drive until the final act. Along the way to said act, Rob Marshall turns in workmanlike action sequences without a hint of flair, and the film's 3D is impressively naturalistic, occasionally eye-popping, and generally unnecessary.

Many of the critics who have seen the film already gave it scathing notices, but On Stranger Tides is trickier than any run-of-the-mill cash-in. It is a complete and total blank slate; a film that the studio, sensing demand, felt obligated to make, and the audience, knowing it was made, feels obligated to see. The same critics who trashed the movie likely had no interest in seeing a fourth Pirates of the Caribbean film, while the audience at the screening I attended were pleased enough, because they went in expecting to be pleased. Much of it does not work, but it is designed in a way that plays so into the audience's expectations that they will get whatever they expect to get out of it, more or less. Still, if your dollars are precious, rest assured that even if you have fun, you will take nothing of substance from On Stranger Tides, and that On Stranger Tides has nothing of substance to offer.