Rarely has the Hollywood game of musical director’s chairs been played more strangely than in the case of this summer’s two big super-hero movies. Brett Ratner was once inked to helm the new “Superman” picture, but he ankled the project after casting and budget problems arose. Meanwhile Bryan Singer, who’d overseen the first two episodes in the “X-Men” franchise and was supposed to do the third, left to take over “Superman Returns.” So Ratner assumed the reins of “X-Men: The Last Stand.” Singer’s take on the Man of Steel is still more than a month off, so one can’t speculate on it, but on the evidence of this installment of the mutant-vs.-mutant saga, all the directorial dancing appears to have been a case of rearranging the deck chairs on the Titanic, so to speak (the ship, not the movie). “Stand” falls pretty far, pretty fast, winding up for all the bombast rather wan and pedestrian.

I must confess that despite their enormous success I wasn’t terribly impressed by Singer’s two X-Men features–in fact, I found them fairly tedious, overstuffed with characters and leadenly plotted, and encumbered by heavy-handed analogies to contemporary social problems. Ratner’s take on the franchise takes up the story where Singer’s second left off, with “Cyclops” Scott (James Marsden) mourning the death of “Phoenix” Jane Grey (Famke Janssen) and “Magneto” Eric (Ian McKellen) and his minions (including Rebecca Romijn’s “Mystique” Raven) continuing his mutant war against not only the mere humans but the accommodating mutants represented by Professor Xavier (Patrick Stewart), “Wolverine” Logan (Hugh Jackman), “Storm” Ororo (Halle Berry), and their small army of students. The plot hook this time around is the announcement that a “cure” for the mutants’ condition has been devised by a pharmaceutical firm headed by Warren Worthington (Michael Murphy)–which particularly enrages Magneto, who holds the position that their extraordinary powers don’t represent a disease that needs curing. At the same time, “Phoenix” literally arises from the dead and, because of her enormously enhanced powers, may become the instrument through which he and his band of unmerry men and women finally win out. (Xavier’s throwaway explanation for her resurrection is unintentionally risible.)

There’s a weird dichotomy in “Last Stand” that’s almost as extreme as the one we see in the resurrected Phoenix–an appropriate name, as it turns out–who can be sweetly docile one moment and turn violently destructive the next. On the one hand, it’s more obviously comic-booky than Singer’s movies were; at times it comes closer to “Fantastic Four” than the previous installments in this series. (So many new mutants are added here–like Kelsey Grammar’s “Beast,” Vinnie Jones’s “Juggernaut” and Ben Foster’s “Angel”–that you might call it “The Fantastic Forty.” Perhaps to compensate, some of the older characters–Cyclops, Mystique, and Anna Paquin’s “Rogue”–get much shorter shrift this time around, and a few old friends are rather summarily killed off.) On the other hand, the “message” component is even more pronounced this time around, which puts more of a burden on McKellen, who has to deliver so many over-ripe speeches in the picture that even he becomes tiresome by the end. (And one can only hope that his final line after he realizes that he’s unleashed Armageddon–“What have I done?”–was actually intended as a take-off of Alec Guinness’ closing moan in “The Bridge on the River Kwai.”) There’s a further curiosity to “Stand” in that the mutant “cure” is an antibody derived from a young boy played by Cameron Bright, who’s not only as blank and dull as he ordinarily is but is playing essentially the same part he did in the dreadful “Ultraviolet”–just another way in which this movie seems awfully familiar.

In a picture like this, the effects take precedence over either plot or performances, of course, and they’re okay, if hardly outstanding, especially in the elaborate final confrontation, which does go on. Among the humans Jackman, Berry, Stewart, and the heavily-made-up Grammer make fairly strong impressions, as does McKellen, camping it up rabidly, though he can’t invigorate things even to the extent he did “The Da Vinci Code.” Most everybody else just rumbles around in the background, and it’s especially sad to see veterans like Josef Sommer and Bill Duke tepidly going through the motions, in scenes that are embarrassingly poorly directed, as the President and his Secretary of Defense. (One also winces at the talented Shohreh Aghdasgloo’s excruciating turn as a prune-faced scientist.) Dante Spinotti’s cinematography is just a little too garish and John Powell’s score a mite overbearing, but toning either of them down wouldn’t have made a great deal of difference.

“X -Men: The Last Stand” will probably satisfy series fans, at least initially, though as they reflect on it later they may decide it’s not much fun–the same trajectory devotees followed with the last three “Star Wars” movies. Let’s hope Singer will have better luck than Ratner.