On the strength of playing about a dozen close-to-the-edge types throughout the '80s, culminating with his work as an escaped mental patient in The Dream Team, Michael Keaton got to be Batman. Twenty years later it's still his best-known role—though Ray Nicolette, his cocky ATF agent from Jackie Brown, is probably his best. While his star has undeniably faded, he remains the actor who got closest to the conflicted nature of Bruce Wayne, and can still carry that ability into excellent work. All of which is further aided by his current dedication, in The Merry Gentleman, to filming every crease and crow's foot in his 57-year-old face. He knows that some vain attempt to hide his fading looks would betray the mood of his directorial debut, this earnest, weighty movie about aging, loneliness and faith.

Keaton is a contract killer named Frank, suffering from the kind of suicidal depression that typifies Christmas in Chicago. He falls in love with the angelic image of a woman named Kate (Kelly Macdonald) when he sees it through the scope of his high-powered rifle. From a ledge across from Kate's office, Frank turns his sight to the businessman on the floor above hers and eliminates him with one silenced shot. He then removes his hat, steps up onto the ledge and summons the will to jump. At that moment, Kate steps outside, looks up to watch the falling snow and spots Frank. She screams; he falls back to the roof and vanishes. For him, it turns out, vanishing is as normal as offing businessmen and attempting suicide. Even after they develop a strange, careful friendship, Frank remains an intriguing blank in Kate's life. He disappears and rematerializes at will, eager to help with a load of man trouble (including an abusive cop ex-husband) while steering clear of his attraction to her.

Two police detectives question Kate about the connection between the mysterious man on the ledge and the dead one in her building. One of them, Murcheson (Tom Bastounes), falls in love with her. (If it weren't for Frank, Kate would have nothing but damaged cops in her life.) Murcheson's murder investigation develops alongside his attempts to take her out. He's terrible at the dating, but great at the investigating. Thus he's led to Frank, certain he's found the killer but unable to catch him without losing Kate. The story continues like this, an uneven mix of serendipity and plot machinations.

The Merry Gentleman is nearly an excellent three-way character study of isolation and regret within the confines of a muted crime plot. But Keaton, as superb as he is with actors (most likely owing to his being an underrated actor himself), doesn't have the directorial delicacy to balance it. He slides awkwardly into comedy at times, as if desperate to break from a plot he senses is weighted beyond control, and into heavy symbolism at others—the ominous churches and statues of Christ don't mean much. Still, this is frequently a fascinating movie. Keaton directs individual scenes with an understanding of heartbreak and miscommunication—most compellingly, he finds a great deal of subtle pathos in the many conversations between Kate and her two suitors. By the end, however, the truly fascinating question is why an aging movie star—always more at home playing unbalanced over suave—felt compelled to explore this vigorously sad story. Given the energy he focuses into it, Keaton seems to be implying that he should have been doing this kind of work from the start, instead of blowing two decades on Multiplicity, Jack Frost and failing to get Ray Nicolette a movie of his own. R.

SEE IT: The Merry Gentleman opens Friday at Fox Tower.