Johnny Depp adds another notch to his memorable gallery of film roles with his portrait of John Wilmot, the debauched Second Earl of Rochester who went head to head with King Charles II in the late 1600s. Opening with the Earl telling the audience that they won't like him by the time his story has been told, "The Libertine" quickly throws one into the filth and grime of 17th-century England. It's a brutally realistic evocation of the time -- perhaps the most authentic ever consigned to film -- and one that makes a mockery of prettified and overly art-directed movies like "Barry Lyndon." The rapier wit dialogue of playwright Stephen Jeffreys, adapting his own play to the screen, sings, too; these are words that stick with the viewer. Buoyed by Michael Nyman's insistent but haunting score and the effectively underplayed, candlelit cinematography by Alexander Melman, "The Libertine" adeptly sets a mood that is highly seductive. (It's also sexually forthright in a manner rarely seen onscreen but highly true to its time and place.)

It all soon runs out of steam as its story sputters to a halt, becoming sidetracked by the less interesting dalliance of the Earl and Elizabeth Barry (an underused Samantha Morton), an actress whom he rescues from career oblivion. That part of the film -- and a pulling back from Depp's more negative persona, such as in his mistreatment of his wife -- is too conventional, even hackneyed. It's a shame because so much of "The Libertine" -- including John Malkovich's chilling portrayal of the King -- really stands out. A fine feature debut for director Laurence Dunmore, "The Libertine" is more of a calling card for his future work than a fully rounded triumph in its own right. Starring Johnny Depp, Samantha Morton and John Malkovich. Directed by Laurence Dunmore. Written by Stephen Jeffreys. Produced by John Malkovich, Lianne Halfon and Russell Smith. A Weinstein Co. release. Drama. Rated R for strong sexuality including dialogue, violence and language. Running time: 130 min