Sweet and colorful-these are the key attributes of any marmalade. The same elements are found, too, in the Roundabout Theatre Company's production of Mr. Marmalade, a new play by Noah Haidle. But there's something much more sinister to the title character than can ever be attributed to the innocent, sticky spread.

Mr. Marmalade is the imaginary friend of four-year-old Lucy (newcomer Mamie Gummer). Left alone most of the time by her single, working mother (Virginia Louise Smith), Lucy gives new meaning to the term "precocious." She invents an imaginary buddy (Michael C. Hall of Six Feet Under) who is something of a corporate bastard, abusive husband, and coke addict rolled into one, complete with affable personal assistant (David Costabile). This isn't enough, of course, to drive her to divorce him when she falls in love with Larry (Pablo Schreiber), suicidal five-year-old supreme.

If you're having a hard time wrapping your head around this, you're not alone. As far as production goes, Mr. Marmalade is an extremely pleasing, enormously funny parody of adult attitudes and drama. Splashed with bright colors in the wallpaper and costumes, Lucy's home provides the perfect setting for her to play house and doctor. Director Michael Greif (Rent) smoothly blends the real and imaginary components of Lucy's life. There are brilliant fantasy scenes filled with the fun of dressing up, fake fine dining, and a full-on junk food fight that will make the child in anyone smile. But there is also a gruesome, gory scene of domestic abuse that appears quite out of the vein of the rest of the play.

It is unclear what message Haidle means to convey through this unexpected violence. In other scenes, the characters' inner-turmoil appears more humorous than horrifying. In Lucy's and Larry's lines, Haidle takes every typical phrase likely to be overheard-and interpreted out of context-by small children and turns them on their head. The two kids, mimicking adult concerns with playful dramatic flair, point out how ridiculous these may sound to anyone who does not actually have to deal with them.

This is well enough on the surface, but it is not nearly enough to make us consider why Lucy takes her imagination to such extremes, bringing her extraordinary, but clearly fabricated conflicts, into her real relationships. Are we supposed to pity her as a troubled child confronting adult problems much too soon (at least in her head) or be proud of her for trying to tackle sophisticated situations with a maturity beyond her years? Or, following the example of Mr. Marmalade, is the bottom line that we just need to hire a personal assistant to clean up our messes?

For the answers, it may be wise to look to Lucy herself. Her decision to frolic outside with Larry at the end of the play is the first time we see her leave her house and fictional world behind. This is a relief after seeing the havoc Mr. Marmalade wreaks, but we cannot really know if Lucy is better off when she sets aside her active imagination. As Haidle wryly observes in narration at the beginning of one scene, every story "ends in death ... if you follow them long enough." To put it simply, we do not get to follow Lucy's story long enough to understand her trials with her fictional friends. We know that Lucy has experienced a tragic enough set of imaginary circumstances to warrant this respite in the real world. It is Lucy's real world, though, that reveals so little of itself in the play, leaving us to wonder which world is really better for her after all.

Gummer, fortunately, captures the glee and despair of childhood convincingly enough to make her performance transcend these difficulties. Her feet, specifically, demonstrate what it means to act like a kid. In each scene, Gummer consistently channels Lucy's excited and nervous energies into the shakes and slides of her animated limbs. Schreiber, as another adult-turned-kid in the role of Larry, practically embodies a juvenile Napoleon Dynamite but is disappointingly absent for much of the play. His charming but infrequent presence cannot attract him to us enough to persuade us that she should abandon Marmalade for him.

Maybe that is the problem. As much as Mr. Marmalade appalls us, there's a reason why Lucy hangs onto him for so long. "I hate being all alone," she admits almost begrudgingly near the end of the play. Loneliness is often reason enough to remain in otherwise unhealthy relationships. Mr. Marmalade sheds a childlike, bright light on this insight, but never achieves the adult complexity needed to make this earnest piece of theater really grow.