Unbeknownst to most Americans, not all the Puritans left England to establish a colony that would eventually become the first state to endorse gay marriage. Quite a few stayed home to help overthrow -- and behead -- the king and set up a regime so lacking in entertainment value its subjects couldn't wait to get their monarchy back. No mean accomplishment, to be sure.

But all that took place years before The Libertine opens, in 1675 or thereabouts. The monarchy has been back in power for a decade and a half, and there's a new king, Charles II (John Malkovich), on the throne. Still, all is not well, and Charles suspects the monarchy might be unrestored at any second. So to whom does he turn in his hour of need? Why, to "The Libertine," of course.

The "Libertine" in this case is John Wilmot, the second Earl of Rochester (Johnny Depp), an accomplished poet and even more accomplished drinker and debaucher.

Why Charles turns to Rochester is one of those blue-blood things most Americans can't make head nor tail of. It seems Rochester's father did the king a favor so the king did Rochester a favor and now Rochester owes the king a favor, or so thinks the king.

What Charles wants is no simple task. He wants Rochester to make speeches for him and write a play. But not just any play -- a play worthy of Shakespeare. It seems Charles' plan to repopularize his regime is for Rochester to become his Bard. All of which is well and good, except that popularity is the exact opposite of what Rochester wants -- something he makes clear in his opening monologue.

"You will not like me," he tells the audience. "The gentlemen will be envious, and the ladies will be repelled. You will not like me now, and you will like me a good deal less as we go on."

That of course may or may not be the case, but it's at least one reason why casting Depp as Rochester was nothing short of genius.

Depp has a talent -- no doubt a natural one -- for playing this kind of character. He can be terribly attractive and utterly revolting all at once, something he accomplishes numerous times in The Libertine, most notably in his last days, when all the libertining catches up with him at once.

Another reason Depp works is that The Libertine is a challenging story to bring to the screen. Set in the late 17th century, The Libertine, based on a play by Stephen Jeffreys, reads much like a Restoration drama. In fact, most of the play -- er, movie -- takes place inside a Restoration theater, where Rochester, recently returned to London after being banished for bad behavior, decides what he really wants to do is devote his life to making London's least successful actress, Elizabeth Barry (Samantha Morton), its most renowned.

Picking up on the motif, Laurence Dunmore, in his directorial debut, lights Libertine as if it were a play -- a 17th-century stage play. The colors are subtle at most, lights flicker constantly and performers work in near darkness much of the time, whether in the theater or the local public house.

Neither is there a shortage of dialogue, some of it in the form of Restoration stage lines. Most of it is mercifully easy to follow, though slowpokes in the audience might be tempted to turn on the subtitles. (It helps, honest.)

And it doesn't hurt to have Malkovich as the king, though a very restrained king, to be sure. Malkovich brings all his intelligence to bear on the part, making Charles II an oddly sympathetic, if not entirely lovable, character. And let's face it, if you're going to have to listen to 114 minutes of Restoration dialogue, you want to hear it from the mouths of intelligent people.

And intelligent people who can not only act but interact. Malkovich and Depp have a screen chemistry that brings out the best in both performers, and it isn't long before The Libertine becomes less stagy and more fluid, picking up speed as it moves along.

Little-known in the United States -- or even in England, where monarchs are more often than not treated like royalty -- The Libertine managed to win a British Independent Film Award (Best Supporting Actress for Rosamund Pike, who played Rochester's long-suffering wife) and garner seven BIF nominations, including best film, director and actor.

More importantly, it fills a niche we hardly even knew we had. That alone makes it worth a good hard look.