Arbor and Swifty are two teenage boys growing up in a poor and run down area of BradfordinWest Yorkshire. Arbor suffers from hyperactivity disorder, which often gets him into trouble even when it is not his intention. When the boys are suspended from school after a fight, they decide to earn money collecting and selling scrap metal. They quickly realize that stealing copper from telecom, railway, and power utilities can be lucrative.
They sell their scrap to a local scrap dealer, Kitten, who owns at least two horses and competes in amateur harness racing. Kitten allows Swifty to work with the horse, once he realizes Swifty's surprising affection for and natural talent with horses. Kitten also lets the boys rent a horse and a cart to collect scrap metal.
Arbor is envious of Kitten's kindness toward Swifty. Arbor decides to steal pieces of scrap from Kitten and sell them, along with some other scrap, to a dealer in Huddersfield. The plan ends up backfiring; Arbor is refused entrance at the other dealer, and when he makes a deal with some men who offer to sell the scrap for him, they recognize it as stolen and keep the money. Kitten finds out and physically intimidates Arbor into stealing a specific piece of high voltage electric power transmission wire to make up for his loss. The boys are not fully aware of the dangers of high voltage wire. Arbor cuts the wire and Swifty helps to lift it, but is electrocuted and killed.
Arbor is devastated and Kitten is arrested, telling the police he is responsible and allowing Arbor to escape blame. Arbor sits resolutely outside Swifty's mother's house. After several rejections, his own mother finds him and takes him home. He refuses any contact by hiding under his bed, until Swifty’s mother finally comes to him.
In a final scene, Arbor takes care of the horse Swifty adored.
^Bradshaw, Peter (24 October 2013). "The Selfish Giant – review". The Guardian. Archived from the original on 30 January 2016. Retrieved 4 November 2014.
