‘Martian Child’ all too earthbound

The story of a single man who reluctantly takes a weird kid under his wing and ends up with a kooky, cobbled-together family of his own, “Martian Child� would like to be “About a Boy (Who Thinks He’s a Martian)�, but, disappointingly, it doesn’t even come close.

Based on a novel by science fiction writer David Gerrold (who loosely based the book on his experiences as a single, gay science fiction writer adopting a 6-year-old boy), the movie stars John Cusack as David Gordon, a straight science fiction writer who adopts a 6-year-old boy two years after the death of his beloved wife. The kid is called Dennis (Bobby Coleman), and he’s a skinny, squeaky-voiced oddball whose many eccentricities include wearing a weight belt to keep from floating away and walking around inside a cardboard box to protect himself from the sun.

David, though, can relate. He too was once an ostracized kid who took refuge in his imagination, and look at where he is today. (In a super-swank modernist pad in the Chicago suburbs, watching his bestselling novel get turned into a movie.) For me, the relating didn’t come so easily, probably because the Dennis character --a whispery, white-faced, parasol-twirling recluse -- conjured up a disturbing conflation of several late-career Bette Davis characters in my mind. David eventually wins Dennis over with a pair of sunglasses and a tube of sunblock and brings him home, against the advice of his highly strung older sister, Liz (Joan Cusack). Parenting a troubled kid turns out to be harder than David bargained for. For one thing, Dennis insists on eating nothing but Lucky Charms. For another, he takes to stealing David’s personal items (passport, wallet, photos of his dead wife) to “learn how to be human.� For this, he’s busted by child services honcho Lefkowitz (Richard Schiff), who never thought David was up to the job in the first place.

Clearly, Lefkowitz is wrong. Once David makes the decision to become Dennis’ father, his commitment is unwavering, to the boy’s advantage and the movie’s detriment. Unlike Hugh Grant’s cool customer Will in the Weitz brothers’ “About a Boy,� David has almost nowhere to go in the story. His role is to be patient, and then more patient as Dennis’ eccentricities pile up to the point that even David begins to doubt whether the kid isn’t telling the truth about his provenance.

Screenwriters Seth Bass and Jonathan Tolins and director Menno Meyjes (“Max�) give Dennis inexplicable powers, like the ability to taste the different colors on M&Ms; and an apparently paranormal knack for timing traffic lights, and occasionally saddle him with awkwardly grown-up, shrink-wrapped, touchy-feely lines like, “That feels so good,� when David encourages him to smash a plate.

If Dennis has any childlike qualities, they are kept under wraps for the sake of teasing out the possibility that Dennis may be telling the truth about where he’s from. The more the movie explores this possibility, however, the less it can delve into the nut of Dennis’ problem, and the less it can explore David’s attempts to understand him. As a result, the relationship feels static until the very end, and Coleman’s performance, which appears to have been heavily directed, is too mannered and eccentric to be affecting.

David has been having trouble getting to work on the sequel to his bestselling novel, to his agent Jeff’s (Oliver Platt) chagrin. But his ever-deepening devotion to Dennis leads him in another literary direction. As the suddenly devoted but totally perplexed father of an underaged wacko, Cusack gives off his usual sparky charm, especially when spouting some of his geeky erudition. (A speech about the unbelievably improbable physics of life on Earth is especially good.) But ultimately what “Martian Child� lacks is reciprocity: David’s role is to wait for Dennis to come around and trust him, so there’s nothing in the way of surprise or revelation.

Other characters, such as David’s eventual girlfriend and late wife’s best friend, Harlee (Amanda Peet as a blandly supportive helpmeet in a wardrobe that could cause retinal damage), and the shrill, put-upon Liz are predictable and one-dimensional flip sides of the girl coin, and Anjelica Huston is wasted as David’s editor. In a ridiculous scene, she organizes a black-tie gala to celebrate the turning in of the first draft of David’s manuscript for the sequel to his bestselling book. On what planet does that happen?

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“Martian Child� MPAA rating: PG. Running time: 1 hour and 48 minutes. In general release.