The 24-year-old actor plays the role of Simon in Henry Blake's gritty movie about a teenager who is groomed into a county lines network and the star revealed that he could identify with the plot and hailed the knowledge of the filmmaker.
Harris said: "I got sent the script from my agent and I really connected with the story and the truth of it.
"Henry was so clued up through his work in that world and the movie came from such a place of truth. I really wanted to do it and the character was like nothing I had ever played before."
Dickinson confessed that he could relate to his alter-ego from his childhood experiences.
He told HeyUGuys.com: "I could relate to Simon as there are people who I went to school with who were like him."
'County Lines' marks a vast change from one of Harris' recent roles - in the Disney flick 'Maleficient: Mistress of Evil' - but he revealed that he likes to change it up with his roles.
He explained: "It's always a new environment on each film. It's challenging and keeps you on your toes. It helps you deal with different scenarios and become better as a person and an actor."
Harris explained that he is drawn to projects that are close to his heart but he found the experience of 'Maleficient' "mental".
He said: "I like doing different stuff and am more interested in doing things that I care about, but doing things like 'Maleficent' are fun and mental at the same time."