On his own after his twin brother's death, Milo, a 12-year-old boy, becomes increasingly isolated from the world around him as he struggles to fulfill the promise made to his brother of completing the go-cart they had begun working on. However, his isolation and refusal to speak create dilemmas and confrontations with the world around him whose help he desperately needs. At the same time, Milo's parents find their relationship falling apart and are helpless in supporting Milo, whose presence constantly reminds them of the son they lost. Thus, finding himself on his own to complete the go-cart, Milo tries to steal from a junkyard, but is caught by the junkyard owner, a scruffy and scary looking man. Only days after his scrape with the junkman, Milo discovers that his father wants to get rid of the go-cart to help him move on, and Milo sees no other way than to ask the junkyard owner for help however scary that idea seems to him. After a bumpy beginning, the two form an unspoken friendship and are finally able complete the go-cart and Milo finds some hope in carrying on a life without his brother.