David is wowed when Dennis is able to do some seemingly strange things such as taste the different colors of M&Ms while blindfolded, make lights turn green, make baseball players score home runs, etc. Dennis chalks it up to "Martian wishes", of which he has a strict limit, but still he shares one with David - but only to be used on something very, very important.
Life with David and Dennis is not without its trials, however. Soon things come up missing, both at home and at school. It seems that Dennis has a "mission" from Mars and that it involves him collecting various items from people. He takes scores of Polaroids, pasting them all over his room, he will only eat Lucky Charms and he wears a weight belt made of duct tape and large batteries to keep the gravity of Mars from pulling him back. His school deems him too different from the other kids and essentially kicks him out. When Dennis accidentally knocks over a glass item on David's desk and shatters it, he thinks David is angry with him, but instead, David explains that these are just material things and together, they destroy all the plates in the kitchen, eventually squirting ketchup all over one another and the kitchen, having a grand time. Unfortunately, this is the very time that Mr. Lefkowitz from Children's Services comes for a visit to see how things are going. After speaking with Dennis, seeing the mess and seeing the vast collection of items in his room, including things like David's passport, he decides that their case must go up for review.
David and Dennis decide that while at home, Dennis can be from Mars, but when he goes out into public, he needs to be like everyone else. He seems to get along better in school and things start going more smoothly. During all of this time, David was supposed to be writing the sequel to his best-selling book, Dracoban. Instead, he finds himself compelled to write the story of he and Dennis. While at a party thrown by his publisher to celebrate his upcoming sequel, instead of handing over the first draft of The Revenge of Dracoban, he instead hands her Martian Child and she is incredibly upset. As she is reading him the riot act, she asks, "Why can't you just be like everybody else?" and David has an epiphany about Dennis.
Unfortunately, Dennis has decided that the Martians are coming back for him and makes his way to the roof-top catwalk of the observatory where he was first found after being abandoned by his mother. The sight of that little boy with his disheveled suitcase is truly heart-breaking. As David opens his heart to Dennis, he finally realizes that not all parents leave.
Whether Dennis is truly from Mars is somewhat left up to the imagination, but by the end of the film, you see that what he really needed all along was someone who would always be there for him. Joan Cusack is wonderful as always as David's sister, Liz, as are Amanda Peet as Harley, David's best friend and neighbor and Oliver Platt as Jeff, his wily manager. Bobby Coleman is infinitely believable as the fragile "alien" child and John Cusack was just made for this role. So filled with self-doubt, yet brimming with love for this difficult-to-understand child. In watching the special features, you get a chance to hear from David Gerrold (He wrote "The Trouble with Tribbles" episode of the original Star Trek, along with numerous books) and his son, along with the writers and directors of Martian Child. I was very interested to see the family that inspired this wonderful story. There are also a slew of deleted scenes, most of which I think belonged in the movie, along with two featurettes, one on the family and one on the making-of Martian Child.
Martian Child is an incredibly touching movie, but also one filled with many comedic moments. If you've ever spent time with an unusual kid, like that one who has made up his own language or just marches to the beat of a very different drum, you would do well to see Martian Child. Make the time to see this wonderful film. Highly recommended.