14-year-old Elijah "Eli" Solinski lives in Detroit with his stern adoptive father Hal, a widower. While scavenging an abandoned building for copper wiring to sell, Eli discovers the aftermath of a skirmish, with armored corpses and high-tech weaponry strewn about. He picks up a strange weapon, but drops it and flees after it mechanically activates. That evening, Eli's newly paroled older brother Jimmy, Hal's biological son, returns home to Hal's chagrin. Eli dreams of the weapon and sneaks out to retrieve it. Sneaking back in, he overhears Hal and Jimmy arguing. Jimmy owes $60,000 in protection money to Taylor, a local crime lord, and asks Hal to help him steal the money from Hal's employer. Hal refuses and kicks Jimmy out. The next night, Hal catches Jimmy and Taylor breaking into his office's safe. Hal is unwilling to walk away, so Taylor shoots and kills him. Jimmy kills Taylor's brother in the ensuing scuffle and flees with the money. Jimmy convinces Eli that Hal is stuck at a work emergency and wants to meet them at Lake Tahoe. Eli secretly packs the weapon, and they leave moments before Taylor and his gang arrive to ransack the house. Taylor vows to kill Jimmy, as well as Eli to avenge his own brother's death..