Their friendship is forged on the football field and in the forests, through boyhood pranks and predicaments. Inseparable since their fistfight on the grade school playground, Gunner and Ronin are known as the Siamese Twins by the small town of Oak Hills. When Ronin loses his mother to a drunk driver, Gunner comforts him. When Gunner is attacked by a mountain lion, Ronin rescues him. Yet they couldn't be more different. Gunner is a goofy white boy; Ronin is a confident Native American. Gunner is tall and strong; Ronin is short and quick. Gunner loves his classic truck; Ronin loves his horse. Gunner is a teddy bear; Ronin is a risk-taker. During the summer preceding their senior year of high school, the seventeen-year-old boys embark on a 5-day canoeing adventure to grow a few chest hairs. On the final day of their voyage, they see a girl floating on an inner tube toward a treacherous waterfall. They react with their water rescue training. Gunner grabs the rope and Ronin the lifejacket. They race to the river's edge, Ronin ties a loop around his waist, and Gunner fixes the other end to a tree. The rope proves too short and Ronin signals for Gunner to cut it so he can swim out. Gunner raises his knife and remembers all the adventures shared with his best friend. He slashes the lifeline and Ronin swims hard for the victim. He reaches her and propels her to the far bank, but the current pulls too strong and he gives her a final shove into a safe eddy before he is carried over the precipice and falls to his death. Gunner denies the loss and mires in survivor's guilt. He carries his burden alone. Until he meets Rebecca, a fugitive running from her own demons. He shares his grief with her and mutual attraction sprouts. Gunner encourages her to follow her passions. He even defends her from an abusive ex-boyfriend. But when Rebecca breaks and confesses Ronin saved her from the waterfall and she could have prevented the tragedy, Gunner rejects her. Unable to deal with her o