Martian Child

He's the film's saving grace as a widowed science-fiction author who tries to work through his grief over his wife—and realize their dashed dreams of parenthood—by adopting a little boy.

The movie leaves no heartstring untugged.

...[a] film about the love between a maladjusted child and a lonely adult promoting mutual healing.

John Cusack plays the fake version of writer David Gerrold, the guy who wrote the Tribbles episode of Star Trek and who also really did adopt a troubled eight-year-old who thought he was from Mars.

Dennis (Bobby Coleman) is a weird kid who thinks he's from Mars. David (John Cusack), a science-fiction writer/widower, adopts him anyway.