"The Other Boleyn Girl" pretends to be a serious historical romance, but it's really just a bodice-ripper, a cheap Harlequin paperback dressed up in frilly clothes. Imagine skit night at the Renaissance Faire and you'll have a pretty good idea of what's going on here.

Based on Philippa Gregory's historical-accuracy-be-damned novel, the story presents the Boleyn sisters, Anne (Natalie Portman) and Mary (Scarlett Johansson). Anne is the older one (though she was younger in real life), still unwed when Mary ties the knot with good-hearted William Carey (Benedict Cumberbatch), and pleased to be a saucy single gal. Her conniving father (Mark Rylance) and uncle (David Morrissey) have a plan, however, to increase the family's social standing: They'll invite King Henry (Eric Bana) for a visit, and then throw Anne at him as a potential mistress!

The reason they assume King Henry will go for this is that he really, really wants a male heir, and so far his wife, Catherine of Aragon (Ana Torrent), has shamefully failed to provide him one. Also, Henry apparently has no decency or scruples and will gladly sire a bastard with any attractive woman who offers her womb to him. That is (or was, anyway) one of the perks of being the king of England.

Anne objects at first to being the family whore, then gets over it (pretty quickly, actually) and flirts brazenly with the king when he arrives. When the king injures himself in a riding accident, for some reason the family sends Mary in to treat his wounds, even though it would have made a lot more sense, plotting-and-scheming-wise, to send Anne. The result, predictably, is that the king gets a crush on Mary, who wasn't even trying to seduce him.

And so now the sisters, who used to be all giggly and gossipy and hip, are totally mad at each other. Mary's husband doesn't seem to mind the idea of his wife being the king's mistress, though Mary and Anne's mother (Kristin Scott Thomas) -- who once had a title and property herself and gave it up to marry the man she loved -- finds the whole thing distasteful.

Then a lot more stuff happens. Say what you will about this movie, there's no denying a lot of stuff happens in it. Anne secretly marries Henry Percy (Oliver Coleman), which angers the king and gets her exiled to France for a while. Then she returns and acts more charming and seduces Henry after all. Then there's some weird stuff with the Boleyns' brother, George (Jim Sturgess), and then there's a declaration that the queen -- you know, the one Henry's actually married to -- can't possibly produce a son at this point. How do we know? Because, as someone loudly announces, "The queen no longer bleeds!" This made me laugh more than it should have.

Though the screenplay adaptation was written by super-scribe Peter Morgan ("The Queen," "The Last King of Scotland"), there's only so much he could do with the soapy, melodramatic material, and British TV director Justin Chadwick can't iron out the kinks, either, despite his august cast. Anne is appalled one minute, then willing, then remorseful, then calculating, then jealous -- it's a soup of random, unmotivated attitude changes, and while Portman runs through them dutifully, she never makes sense of them. Johansson is just bland as Mary, and Eric Bana makes Henry VIII one of the dullest kings in recent memory.

The only one I liked was Spanish actress Ana Torrent as Catherine of Aragon. As the beleaguered queen who knows her days are numbered, she exudes great dignity and authority, an understated and affecting performance in a movie full of garish histrionics. King Henry ought to have stayed home and left those ditzy Boleyn girls alone.

Grade: C-

Rated PG-13, brief strong sexuality, brief violence

1 hr., 51 min.