After spectacularly losing a local spelling bee as a youngster, the now 40-year-old Guy Trilby is determined to go back and change it. Having developed his spelling ability substantially over the decades, he decides to enter the National Quill Spelling Bee after discovering a loophole which states that anyone past the 8th grade cannot compete. Having given up on academic achievement before he passed 8th grade, the contest's judges struggle to deny him the opportunity to compete despite arrant fury from parents of potential winners who believe that his age now gives him an advantage. Initially rude and insulting towards his pre-pubescent competitors, he soon starts to develop a friendship with Chaitainya; an enthusiastic young boy with no friends who Guy takes under his wing. However, not everyone's happy with what Guy ends up teaching Chaitainya about the world.
Guy Trilby is a 40-year-old man who dropped out of high school as a young boy and remains bitter about losing a spelling bee. Thus, now older and wiser, he finds a way to enter the National Quill Spelling Bee by abusing a loophole which states that anyone past the 8th grade cannot compete. As he abandoned his studies before passing 8th grade, he decides that he has every right to qualify for the competition, to the annoyance of entrants' parents and contest officials alike as, of course, his age gives him an unfair advantage despite his educational failures. Along the way he meets a young boy named Chaitainya who appears to have no friends his own age and who Guy Trilby gladly takes under his debauched, f-word riddled wing.
A young girl, Luli, from a small town hitchhikes to Vegas with her father's pistol in an attempt to escape the abuse from her alcoholic parents. On the way, Luli meets Eddie - an unhinged man in a Stetson with dubious intentions - and Glenda, a red-headed druggie on the run. With the simple plan of finding a "sugar daddy", Luli gets into much more hostile situations than she bargained for.
For once, the film's title is hardly a coy allusion or abstract metaphor - Thumbsucker is a movie about, yes, a thumbsucker. More specifically, he's a 17-year-old thumbsucker, a fact that hardly endears him to his schoolmates or family. As would be expected in most any film about a socially awkward teen, the story is ultimately about his maturation (or lack thereof) into the adult world. What it ends up being, however, is more like the chronicle of some hardworking parents stuck with a truly problematic son who's about as unlikable as it gets.
As parents Audrey and Mike Cobb, Tilda Swinton and Vincent D'Onofrio seem an odd choice, but it's an absolutely perfect one. Director Mike Mills may not have the best ear for story or subject matter (the source novel by Walter Kirn, should likely have been left on the unfilmed backlist) but he's dead-on when it comes to tone and casting. A pair of tired out working-class adults in a small Northwest town who can't quite accept being grownups, they have their two boys call them by their first names. Everything around them betrays this hope, of course, with Audrey working night shifts as a nurse at a celebrity drug treatment clinic just to catch a glimpse of an addict TV star she's got a girlish crush on, and Mike as the beaten-down manager of a sporting goods store unable to forget that but for an injury he could have gone pro.