My Dad first showed this one to me as a 12 year old with very basic knowledge of film, but my eyes had a rude awakening as soon as the film opened up.
For me this is Lumet's masterpiece. The script is fast and timed to perfection, the acting is second to none and the execution is simply breath-taking. Over 50 years since it was first released and it's still recognised today as one of the greatest movies ever made. You can't help but get sucked into the story and you almost feel like the twelth man on the jury,
It's a work of magic, simple as that. Check it out!